Unit 2: Education & Development

• Critical/Sensitive Periods – Periods of development where certain cognitive and physical characteristics are most quickly acquired, or when the brain is most adaptable to certain changes.
• Neural Plasticity – The ability of the brain to change its neural pathways and/or synapses.
• Declarative Memory – Declarative memories are those memories that can be consciously recalled and stated, such as facts, directions, or lists.
• Non-Declarative Memory – These memories describe a range of memory types such as skills (e.g. riding a bike) and classical conditioning (e.g. salivating in response to a bell-ring).
• Episodic Memory – Memories about specific events in the past (e.g. my 10th birthday party). This is a type of declarative memory.
• Semantic Memory – Facts that are “abstracted” from any specific experience, such as names of animals, country flags, etc. This is a type of declarative memory.
• Circadian Rhythms – Physiological, behavioral, or cognitive changes that are aligned to a roughly 24-hour cycle. These fluctuations are primarily driven by an “internal clock” that is in turn affected by environmental cues.
• REM Sleep – Rapid Eye-Movement (REM) sleep is the phase in which we dream. It is the last phase of the sleep cycle, and while our eyes move and heart rate increases, our muscles are paralyzed.

Introduce the lesson by explaining the background information below and guiding them through the following activity:

Is the brain’s ability to learn new things constant over the course of our lives? No—the brain is more receptive to changing and learning from the environment early in life, particularly for certain kinds of skills like vision and language.

1. Show this short video that discusses the idea of sensitive periods for development.
2. Ask students to reflect using these questions:
   • How do you think these “sensitive periods” relate to language? Do you think it is easier to learn a new language as a young child or adult?
   • Think about someone you know personally or a celebrity that speaks multiple languages. (This part may turn into a loose discussion with the actual question as a homework assignment.) 
     • Look up or ask this person when they first started to learn a second language, how easy it felt for them, and how confident they feel with their second language. 
     • How “fluent” does this person feel and do they have an accent that carries over from their first language? 

Guide students through the following discussion of an extreme case study that helps demonstrates the importance of sensitive periods of development:

1. Pose the following question to students for a brief discussion:
   If a child is not given the opportunity to learn any language early on during a sensitive period, do you think they can learn language later in life? 
2. Explain the following background to students (if appropriate, additional details to share can be found in this overview of this tragic case of extreme child abuse and neglect): 
   The case of Genie Wiley is the most famous in the study of language and development regarding sensitive (or critical) periods. She spent almost her entire childhood locked in a bedroom, isolated and abused. Since it is deeply unethical to perform an experiment in which a child is raised in an environment where they are not spoken to or played with, up to that point scientists were unsure if a sensitive period for learning verbal language existed. Once Genie was rescued and brought to the children’s hospital for rehabilitation, scientists were curious to see if Genie could learn to speak normally.
3. Show students this video excerpt from a documentary about Genie and what scientists observed from her case. The video link is set to start at 5:13 to avoid graphic images of Genie’s abuse. The story itself may still be disturbing to students so please allow space to process. Ask them to discuss the following questions in pairs or groups:
   • Does Genie’s inability to fully learn grammatically correct English suggest that sensitive periods exist for language?
   • What other barriers could possibly be preventing Genie from learning English?
4. Note the pitfalls of drawing conclusions from single case studies—it’s possible that Genie had pre-existing disabilities that would have interfered with her ability to learn language even if she had been raised normally. There is also the issue that neglect or trauma of this severity is likely to impact the brain as well. 

The following information is teacher-facing and can be utilized to teach students new information in whatever format works best for you and your students.

Key Points:

• Sensitive periods are particular stages of development when we are most predisposed to learn certain functions from environmental input.
• Sensitive periods are thought to be related to phases of increased brain plasticity, when neural connections are flexible and easily strengthened or pruned away.
• The human visual system develops quickly over the first few years of life, and disruption to vision during this time may be later irreversible.
• Sensitive periods for language relate both to the first language we learn as well as our ability to learn a second language.

Plasticity
Brain plasticity, or neuroplasticity, is defined as the ability for the brain to change its physical structure (not just pattern of firing). When we learn new things, experience new situations, or practice skills, the connections between neurons can become stronger, new connections can be formed, and weaker connections can be pruned away. In the launch lesson discussion, we discussed the role of genes in laying down the basic structure of the brain’s neural network, but this initial network is then fine-tuned and changes with exposure to experience as the organism develops. This flexibility allows the brain to adapt and optimize its functioning based on our experiences and needs. Your brain remains plastic and changeable in response to its environment for your entire life, although younger brains are more plastic—especially during sensitive periods. Adolescence is also a time of peak plasticity.

Sensitive Periods in Vision
Periods when we are most predisposed to learn from environmental input are called “sensitive periods” (or, equivalently, “critical periods”). The primary sensitive period for vision occurs during the first few years of life. Neural connections in the visual system undergo significant changes, allowing the brain to adapt and refine visual processing based on the quality and quantity of visual experiences. Visual deprivation or abnormal visual experiences during the sensitive period can negatively impact visual development. However, even beyond the sensitive period, the visual system retains some degree of plasticity, allowing for continued learning and adaptation throughout life, although to a lesser extent. 

Sensitive Periods in Language
The sensitive period for language typically begins in infancy and peaks between ages 2 and 7. During this period of neural plasticity, it is easier for children to pick up the sounds, vocabulary, grammar, and nuances of language. While babies are born with the ability to distinguish all phonemes, over time, children no longer hear distinctions between phonemes that are not important to their own language. Language acquisition can still occur beyond the sensitive period, but it may require more effort, explicit instruction, and practice (there are arguments over whether the learning of a first language itself must take place during a sensitive period). A well-characterized example is that “r” and “l” do not exist as standalone sounds in the Japanese language, while the English language doesn’t have the sound that is more of a blend between the r and l sounds in Japanese. As a result, native Japanese speakers cannot easily pronounce the English r and l sounds, and vice versa.     
 

Have students work in teams to evaluate an early childhood toy. Guide students through the steps below:

1. Identify a toy you know of that young children use.
2. Research what age this toy is marketed for.
3. Research what skills are being developed during that targeted age range (ex: fine motor skills, sorting/categorizing, pretend play etc.)
4. Answer the following questions about the toy:
   • Does the toy target developmentally appropriate skills for the intended age range? Why or why not?
   • Think of ways the toy could be altered to better target developmentally appropriate skill building.
   • How could families nurture similar skills using everyday household materials?

Note: This student-facing guide to a hands-on toy design project allows you to extend this activity into a project-based learning experience.

Introduce the lesson by explaining the background information below and guiding them through the following activity.
 

Much of what we know about different kinds of memory comes from studies of patients who have had memory deficits (amnesia). Clive Wearing is a famous (and the most severe) case of a man who is unable to form new long term memories because of damage to his hippocampus during a viral infection. His case is unique in that he constantly feels like he is “waking up” for the first time. Whenever he sees his wife, he feels like he hasn’t seen her in a long time, and greets her with extreme excitement. Students may be familiar with this phenomena through pop-culture references like the movies 50 First Dates or Memento.

1. Show students this short video showing Clive’s interactions with his wife.
2. Ask them to reflect using the questions below:
   • Clive can’t remember what someone just said but he does remember his wife and how to play the piano. How do you think these two types of memories differ?
   • What other types of things do you think Clive can remember?
   • Based on Clive’s injury (lesion) how long do you think our short term memory lasts?

For additional information, this (older and longer) video describes a more detailed story of Clive’s illness and subsequent life.

Explain the background information below to students to frame the following activity. One very well studied phenomenon in the memory literature is that we are better able to remember items that we heard/studied first and last in a list, whereas we have a harder time remembering items in the middle.
 

Use this activity from BrainU.org for an in-class demonstration of primacy and recency. The overall steps are compiled below:

1. Tell your students that you will present a list of words and they are to remember as many of them as possible without writing anything down.
2. Write the words in sequential order on the board. You can also read them aloud at one word per second. Take the list down after one minute:
   • cat, apple, ball, tree, square, head, house, door, box, car, king, hammer, milk, fish, book, tape, arrow, flower, key, shoe
   • If there are some students in the class who are native speakers of another language, then consider providing a list of words in that language as well.
3. Now ask your students to write down as many words as they can remember.
4. Collect the data on how many students remembered each word, for example: 10 students for the first word, 8 for the second, etc.
5. Direct the students to create their own graphs to represent this data:
   • Graph the order of words and the number of people who remembered the words. (example graph in Explain section)
   • Ask students to reflect on the data with the following questions:
     • Is there a pattern in the data?
     • Were there some words that were easier to remember than others? If so, why were some of them easier to remember?
     • What strategies did you use to try to remember as many words as possible?
6. Explain to students: This experiment helps explain that there are two kinds of memory happening in order for this task to occur.
   • The words read last are still in a person’s short-term memory, while the words read first made it into the long-term memory. These are the recency and primacy effects.
   • The middle words fall somewhere in between and are not as well remembered. Of course, some words may be easier to remember than others due to associations people already have with them.

The following information is teacher-facing and can be utilized to teach students new information in whatever format works best for you and your students.

Key points:

• There are many different types of memory, each dependent on a unique (though sometimes overlapping) set of brain structures.
• The hippocampus is a key brain region involved in the encoding of long-term memories that are eventually stored in the cortex.
• There are many study techniques that make use of what we know about memory to help us better retain information.

Types of Memory
As the case of Clive Wearing shows, there are different kinds of memory. Memory requires not just encoding and storing pure facts but also context. There is the factual memory of what date you attended a party, the association between a song that you heard and the face of the person you danced with, the motor memory of the new video game you played there, the emotions you felt, etc. Over time, your brain strengthens the connections of important memories based on how often you recall them or strong emotional associations, while other memories are forgotten. 

The hippocampus is a brain area critical for stabilizing factual information, also referred to as “declarative” or “explicit” memories, for long-term storage in the cortex. However, not all types of memories require the hippocampus. Skills and habits rely on a region deep in the brain called the basal ganglia, whereas motor memory (such as remembering how to ride a bicycle) relies on the cerebellum. Emotional memories rely on the amygdala, which is located next to the hippocampus deep within the temporal lobe. All of these types of memories are referred to as “non-declarative” or “implicit” memories. For pictures and locations of these brain regions, refer to the lesson on brain anatomy in Unit 1, Lesson 5.
 

Memory and Learning Strategies
Understanding mechanisms of memory can help us develop more effective learning strategies. When remembering a list of items, do you notice that you remember the first few and last few items the best (as shown in the graph below)? The primacy effect is thought to be due to the first few items having the chance to be stored in long-term memory, while the recency effect is due to the last few items being retained in short-term memory. Other evidence shows that we forget things quickly that we have only studied once, but that spaced repetition helps us retain information. Finally, we also know that active recall (testing ourselves), rather than passively reading information, is a much better way to learn (this is called the testing effect).  
 

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The primacy and recency effects mean that both the first items presented in a list and the last items presented in a list tend to be more easily remembered than items in the middle of the list.

Explain the background information below to students to frame the following activity:
One skill that some amnesia patients can learn is how to trace a star while looking at it in a mirror. This suggests that there are certain kinds of “procedural” memory that do not rely on the hippocampus. 

Have students try this task for themselves using this Mirror Tracing Activity Guide from HHMI BioInteractive. Brief directions below:

1. Print out 1 star-pattern-tracing sheet per student and 1 practice sheet per student
2. You will also need a mirror, a piece of cardboard, a pencil, and tape for each student.
3. Have students trace the star on the practice sheet without a mirror.
4. Use the cardboard to block direct view of their hands and prop up the mirror so they can see their hand in the reflection. 
5. Tape their paper down to the desk and have them try to trace the star, starting at the (S) mark. 
6. Time the students as they complete this 
7. Score their tracings based on the score sheet in activity guide
8. Have them repeat the tracings a few times
9. For best results have them do these each day for 3 days to see if they improve over time 

Science in the Classroom (SitC) is a collection of annotated research papers and accompanying teaching materials designed to help students understand the structure and workings of professional scientific research.
 

This annotated paper, “The Original GPS: How We Remember What Happened Where,” examines what happens in human neurons while subjects are playing a memory video game. See the Science in the Classroom Teacher Resource that accompanies the article.

1. Assign small sections of the article to student groups
2. Then have each group present or use a jigsaw method to teach the entire class what is in their part of the article.

Introduce the lesson by explaining the background information below and guiding them through the following activity:
Learning disabilities/differences are biological or genetic differences that alter the function of the brain in a way that directly affects one or more cognitive processes related to learning. Learning differences can make reading, math, writing, or other common scholastic tasks effortful and difficult for affected people. Learning differences tend to be specific to the kind of cognitive tasks related to learning and school, and are not an overall intellectual impairment. The Learning Disabilities Association of America has a nice website explaining many of the most common forms of learning disabilities.

1. Show students this short video, which features young students with learning differences talking about how their brain works and how teachers can help. 
2. Ask students to reflect on the video using these questions:
   • How does traditional classroom design and the physical and social structure of the school environment provide challenges for students with learning differences?
   • What resources are already available at our school to support students with learning differences?
   • How could we make sure our classroom is inclusive and provides support for students with learning differences?

Explain the background information below to students to frame the following activity.
​​​​Many populations of students report that dyslexia and similar reading disabilities are the most well-known learning disability. One of the biggest difficulties that people with dyslexia face is the increased effort and time it requires to read, once they learn how. Dyscalculia is another learning difference that affects a person’s number sense. Dyscalculia is a specific learning disability in which this number sense is dramatically impaired, making all sorts of day to day tasks difficult. 

Show students the following images and ask the questions below each image in order to show them how it feels to have dyslexia or dyscalculia. The second column explains the phenomena. This can be presented as a stations activity, independent reflection, partner work, or whole group lecture. 

Try to read the text in the image:

Image

1. How difficult was it for you to read the text? How much longer did it take to decipher than if the full letters were there?
2. Reflect on how having dyslexia might affect a student in a typical learning environment with no support or accommodations. 

Explanation: One designer, Daniel Britton, who is dyslexic himself, designed a font to help neurotypical people understand those challenges. In this font, about half of each letter has been removed, but with a little more time and effort, most readers can still make out the words. This font isn't meant to perfectly mimic the experience of having dyslexia, but it gives the reader a sense of the difficulty and frustration that one can feel. "What this typeface does is break down the reading time of a non-dyslexic down to the speed of a dyslexic. I wanted to make non-dyslexic people understand what it is like to read with the condition and to recreate the frustration and embarrassment of reading everyday text and then in turn to create a better understanding of the condition," Britton explains.

Determine how many dots are in the image:

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1. How many dots are in this image?  
2. Did you count them one by one or use a different strategy?  Explain to your table partner how you determine the number of dots in the box.    

Explanation: Most people don’t have to count all the dots, but instead immediately recognize that there is a group of three dots and a group of four dots and that 3 things and 4 things are 7 things altogether—notice that there is no counting involved!  This is called “number sense” or the “approximate number system” that allows most people to estimate small quantities very accurately without having to count them. Dyscalculia is a learning disability in which this number sense is dramatically impaired, making all sorts of day to day tasks difficult. People with dyscalculia have a hard time with basic estimation that seems very easy to neurotypical individuals. 

Which image below has more dots?
 

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1. Which image has more dots?
2. How quickly did you determine your answer? How did you decide?    

Explanation: Most people can tell at a glance that the bottom box contains more dots even if they cannot say how many dots that is, exactly. People with dyscalculia will have a hard time doing this estimation and will likely have to count every dot. They also may say that the top image has more dots because that box has more physically larger dots, confusing the issue for them. Number sense allows us to estimate the quantity of something and ignore what color or what size those items are, or even where in space they are located. But with a deficit in this number system, people with dyscalculia have great difficulty in estimation.

The following information is teacher-facing and can be utilized to teach students new information in whatever format works best for you and your students.

Key points:

• Dyslexia is a language-processing disorder that leads to difficulty in reading comprehension and spelling.
• Dyscalculia is a disorder of “number sense,” impacting not only the ability to work with numbers doing math, but also sense of time and spatial ability.
• People with dyslexia or dyscalculia show differences in structure and function and areas of the brain associated with language or number processing, but there is evidence that other regions of the brain can help compensate.

Dyslexia
Dyslexia is most commonly defined as a difficulty in both reading and in learning how to read. The exact nature of the disorder varies from person to person, but the most common symptoms involve difficulties with understanding and processing sounds as well as spelling. It also affects the brain’s ability to translate printed symbols into sounds and vice versa, a critical function for reading. Studies of the brain suggest that people with dyslexia have both structural and functional differences in regions of the left hemisphere associated with language processing, but increased activity in other brain regions suggests that they may help to compensate. Some newer research indicates that dyslexia may be a broader disorder in processing sensory inputs that happens to impair—but is not specific to—reading.

Dyscalculia
Dyscalculia is a learning disability relating to math and number sense. Much like dyslexia, this learning disability is unrelated to a person’s overall intelligence and each person’s experience with dyscalculia may be different. The most well-known symptoms involve recognizing numbers or symbols in math, translating those symbols into concepts, and then working with them to solve math problems like those done at school. Symptoms can also affect sense of time, working with money, and spatial relationships, like reading a map or telling left from right. Research shows that brain areas involved in number processes, especially the intraparietal sulcus (IPS; a groove on the side of the brain in the parietal lobe), are less active or show structural differences in people with the disorder. To help make up for decreased brain activity in the IPS during math tasks, dyscalculic people may rely more on brain areas associated with working memory and attention, which can help but is also more effort and leads to exhaustion.

Explain the background information below to students to frame the following activity.
When advocating for people with learning differences it is critical to ask the people themselves what they need and want. In this activity you will write a letter to the principal requesting specific supports for students with learning differences, specifically dyslexia and dyscalculia, based on an interview with a student with dyslexia. 

1. Show students this video interview of a student with dyslexia. While they watch ask them to answer these questions:
   Other video options: Actor Orlando Bloom, Actor Keira Knightley, Celebrity stylist Janielle McKoy, Football player Deon Butler (4:51-10:28)
   • Describe a few things the student says he struggles with. 
   • What did the student say he feels confident with?
   • What specific examples did the students describe that teachers had done in the past that supported him?
2. Ask students to write a letter to the principal that includes:
   • What are dyslexia and dyscalculia? (based on scientific information they have learned in this lesson)
   • What are some things students with dyslexia and dyscalculia struggle with? What are some things they do not struggle with?
   • What are some supports that can be put into place that would benefit students with learning differences in ALL classes? Specifically cite things the student in the video identified as helpful. 

The following activity can be used as an extension to help students focus on strengths exhibited by people with learning differences.

1. Ask students to go to the article “Signs of Dyslexia” and read about the strengths many students with dyslexia have at different ages.
2. Give students a list of upcoming topics/objectives that will be covered in your class. 
3. Ask students to design an activity for your classroom that draws on the strengths of many students with dyslexia that relates to an upcoming class topic/objective. 
4. Once they have designed the activity ask them to answer the questions below:
   • What strengths does this activity highlight?
   • Why might this activity be more accessible to students with dyslexia?
   • Can this activity also be used by neurotypical students? Why or why not?

Introduce the lesson by explaining the background information below and guiding them through the following activity:
In this lesson we will dive into sleep and how it affects learning. To start, let’s think about sleep rhythms based on age. 

1. Ask students to reflect independently on the following questions. Then ask a few to share out their thoughts:
   • When do you naturally start to feel sleepy? If left to decide, around what time is it easiest for you to wake up?
   • Now think about little kids. When do they usually start to feel sleepy and when do they naturally wake up?
   • Now think about adults. When do they usually start to feel sleepy and when do they naturally wake up?
   • How do these three stages of life compare in terms of natural sleep tendencies? Why do you think natural sleep rhythms are different for kids, teens, and adults?
2. After this silent reflection and share-out, show students this video about the sleep needs of teenagers.

Guide students through the following discussion about the “24/7” lifestyle.

1. Show students this video from Dr. David Dinges talking about the “24/7” lifestyle.
2. Lead a whole-class discussion about some of his key points and questions:
   • Society has created a 24/7 lifestyle that puts our biological needs at risk.
   • Should we be treating a lifestyle issue (lack of sleep) with medication (caffeine)?
   • Early school start times are terrible for adolescents who need large amounts of sleep and who naturally fall asleep late and sleep late.
   • Sleep deprivation has been labeled the leading cause of catastrophic outcomes (crashes and accidents) by the National Transportation Safety Board (NTSB).

The following information is teacher-facing and can be utilized to teach students new information in whatever format works best for you and your students.

Key points:

• There are 5 stages of sleep, divided into REM and Non-REM sleep, which can be measured using EEG and other techniques.
• Circadian rhythms influence when we feel tired, and these rhythms change over the course of the lifespan—especially during adolescence.
• Sleep is important for learning, both because it helps us stay focused and attentive during the day and because memories are actually strengthened as we sleep.

Stages of Sleep
Scientists have shown that there are 5 stages of sleep: Stage 1, 2, 3, 4, and REM (rapid eye movement) sleep, as shown in the sample sleep diagram, or hypnogram, below. Stage 1 is considered “light sleep”: it is easy to wake up, and our muscles are still able to move. Stage 2 is also somewhat light. Stages 3 and 4 are “deep sleep”: it is hard to be woken up, and our eyes and muscles are no longer moving. REM sleep is the final stage in the cycle—this is when we dream, our eyes move quickly and our heart rate increases, even while our muscles become paralyzed. These different stages of sleep are determined by measuring brain waves with electroencephalography (EEG; more about this technology in Unit 3, Lesson 1), eye movements, and muscle tension. Brain waves slow down during deep sleep while during REM sleep, brain waves occur at high frequency, most similar to what is seen in an awake brain.

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The brain moves from phase to phase of sleep as the night progresses. Early in the night, people tend to stay in slow wave sleep for longer periods of time, whereas later in the night, people tend to stay in REM sleep for longer periods of time. Image credit: RazerM at English Wikipedia, CC BY-SA 3.0, via Wikimedia Commons

Circadian Rhythms, Light, and Sleep
Circadian rhythms are the natural, internal rhythms that our bodies follow over a 24-hour cycle, helping our bodies know when to sleep, wake up, and carry out other important functions. A brain region called the suprachiasmatic nucleus (SCN), located in the hypothalamus, acts as the body's master clock, coordinating various physiological and behavioral processes throughout the day. Detection of light (particularly blue light) by the eyes signals to the SCN that it’s daytime. In response, the SCN inhibits the release of the chemical melatonin, promoting wakefulness and alertness. As it gets dark, the SCN sends messages to trigger melatonin release, making you feel sleepy. Environmental factors like jet lag or exposure to artificial light at night can disrupt your circadian rhythms. In addition, circadian rhythms and average sleep requirements change over the lifespan, as shown in the graph below. Normal developmental changes during adolescence shift the melatonin cycle, resulting in later sleep and wake times.

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Sleep needs vary based on a person’s age, with babies needing the most sleep and older adults needing the least. Image credit: National Institutes of Health

Sleep and Learning
During sleep, the brain does not “shut down” or “rest.” Instead, this is a time when the brain gets things done. While we are still learning a lot about sleep, we do know that different stages of sleep contribute to different aspects of learning and brain function, making both quantity (getting sufficient sleep) and quality (having uninterrupted, restful sleep) important. During sleep, the brain clears out waste products and toxins that accumulate during wakefulness. It processes and transfers information from short-term to long-term memory storage. Sleep helps improve cognitive performance, attention, and problem-solving by enhancing the ability to make connections between different pieces of information. The brain also undergoes structural and functional changes for plasticity during sleep to facilitate learning and the formation of new neural networks. 

Instruct students to prepare a proposal for the school board that advocates either in favor of or against a later start to the high school schedule using scientific evidence. 

Students should include:

1. How does your proposed schedule account for the amount of sleep and times of sleep that the teenage brain most requires?
2. What other adjustments and tradeoffs will your change in schedule require, e.g. shifting extracurricular activities, bus schedules, etc.
3. What are the overall benefits and drawbacks to your new schedule?

Below are two possible extension activities related to sleep that you could assign to students:

Sleep Diary
Keep a sleep diary (such as this sample sleep diary from the National Institutes of Health) for 1 week. At the end of the week, have students discuss…

• average amounts of sleep
• tiredness at different points of the day
• consistency of sleep patterns
• what events made it hard to fall asleep

Sleep and Learning Jigsaw
Science in the Classroom (SitC) is a collection of annotated research papers and accompanying teaching materials designed to help students understand the structure and workings of professional scientific research. This annotated paper, “Sleep: No Longer Just for Dreaming” studied how the dendrites of mouse neurons changed during sleep after the mice had learned a task. See the Science in the Classroom Teacher Resource that accompanies the article.

• Assign small sections of the article to student groups to read and discuss during class (or in a computer lab, as the interactive article is web-based).
• Then have each group present or use a jigsaw method to teach the entire class what is in their part of the article

Introduce the lesson by explaining the background information below and guiding them through the following activity:
In this lesson you will discuss how trauma and stress affect the brain. One way that scientists characterize the amount of stress and trauma a person has experienced is through the Adverse Childhood Experiences (ACE) survey. The more ACEs one has experienced, the greater the likelihood of certain health-related issues later in life. 

1. Ask students to confidentially complete the ACE survey. Alternatively, you could simply show the ACE survey and read it together as a class as a reference point for what types of factors we are considering. 
2. Have students reflect independently, in pairs, or as a whole class:
   • What types of circumstances do you think make a child more at risk of having Adverse Childhood experiences? 
   • How might adversity/trauma be different for a child in a place where there is war or an ongoing natural disaster?
   • Based on what we learned about sensitive periods in lesson 1 of this unit, do you think adversity/trauma would have a bigger impact on the brain in young children or in adults?

• Note to teachers: After this discussion it is important to emphasize that while we know ACEs affect brain development, we also know that children’s brains have more plasticity. Effective interventions to support resilience after trauma are a major area of current research. Later in this lesson we will discuss examples of interventions that have been shown to help overcome these effects. 

Guide students through this discussion of correlation vs caution using the steps below:

Step 1: Introduce the idea of correlation vs causation with the scenario below: 

• To develop interventions for the effects of trauma and stress, we have to understand what causes them. This can be complicated! When scientists see patterns in the world, we have to think carefully about how they might—or might not—be related to each other. Consider this example:
• Scientists have observed that people eat more ice cream in the summer. They have also observed that people get more sunburn during the same time period. As a result, they conclude that eating ice cream causes sunburn.
• Ask students to discuss the scenario and if this conclusion makes sense. 
  • Explain: Obviously not - the ice cream/sunburn conclusion does not make sense! This scenario is a classic example of mistaking correlation with causation. A correlation describes the strength and direction of the relationship between variables, while causation indicates that one variable produces an effect on another variable. While ice cream consumption and sunburn may be strongly positively correlated, hot and sunny summer weather is the causative factor for both. 
  • You may show students other examples of nonsensical correlations, many of which have been popularized by Tyler Vigen.

Step 2: Have students consider the strengths and weaknesses of correlational vs. experimental research by comparing the two studies below.
 

Step 3: After learning about each study ask students to independently reflect on the following questions: 

1. Which study tests a specific hypothesis? How is it designed to do so?
2. Which study might provide insights that are more generalizable to a population? Why?
3. How does each study connect to real-world applicability?
4. (Optional connection to ethical issues with neuroscience methods discussed in Unit 3, Lesson 3: How might implicit biases embedded in algorithms used to analyze the ABCD dataset affect the interpretation?)

Step 4: Explain these key takeaways: 

• Correlational research plays an important role in neuroscience as it allows scientists to investigate and understand the relationships between variables without manipulating them directly. 
• Correlational studies can generate hypotheses that can then be tested using experimental or other research designs. They can also provide insights into variables that cannot be manipulated directly due to ethical constraints, as well as investigate phenomena in complex and diverse real-world contexts. 
• Students should keep these advantages and challenges in mind as they consider evidence for how social and environmental factors affect brain development.

The following information is teacher-facing and can be utilized to teach students new information in whatever format works best for you and your students.

Key Points:

• Different brain regions coordinate the body’s stress response.
• Chronic or excessive stress due to trauma or adverse experiences can affect brain development especially in regions related to emotions and memory.
• Research has been limited in determining the causes of observed effects on structure and function, but new large population datasets are yielding new insights into the relationships between different socioeconomic factors and brain development.

Stress Response and the Brain 

The brain coordinates a complex series of physiological and behavioral reactions to perceived threats or stressors. The amygdala is involved in quickly evaluating a potential threat. If it senses a danger, it activates the hypothalamus, pituitary gland, and adrenal glands—the “HPA” axis—to kick off the stress response. This chain leads to the release of stress hormones, particularly cortisol, that help the body respond to the threat (“fight, flight, or freeze”). The stress response is tightly regulated so that the body can be restored to a balanced state once the threat has subsided. The prefrontal cortex helps to mediate the amygdala’s response through slower, more rational evaluation of the situation and thinking about appropriate coping strategies. While the stress response is a natural adaptive mechanism, chronic or excessive stress can have detrimental effects on physical and mental health. 
 

How Stress and Trauma Affect Brain Development 
Major adversity in childhood, such as extreme poverty, abuse, neglect, or trauma (like from a war, or in the case of Genie in Lesson 1 of this unit) can alter the development of the brain. Research in animals subjected to chronically high levels of cortisol as well as in humans who have suffered trauma shows structural differences in the amygdala, hippocampus, and other brain regions that are necessary for helping us decide how to respond to emotional situations. Even moderate levels of adversity, like from a chronically stressful life or from living with low socioeconomic status (SES), may also lead to differences in the brain. However, thanks to brain plasticity, these effects are not inevitable and can be mitigated by social interventions and supportive relationships with caring adults (see more about strategies for social well-being in Unit 4, Lesson 6).

Socioeconomic Factors
Although low SES is commonly associated with chronic stress, it has been hard to conclusively say that poverty directly causes changes in brain development. Low SES is a multi-dimensional concept that includes access to resources (like healthcare and good food) and is sometimes more accurately represented by social factors (like the level of your parents’ education) rather than strictly by family income. Recent studies have taken advantage of large longitudinal studies (like the ABCD Study®) that are following children and their families for years as they grow to learn more about how their environment can shape their brain development. These analyses can go beyond family income to look at correlations with the impact of other social variables such as racial disparities or the availability of public assistance programs.

Many newer studies are looking to see what kinds of interventions might make the biggest impact on the brains and the lives of children from low SES households. Comprehensive early childhood interventions designed for both children and their adults—for example, low cost or free preschool paired with therapy and other support for family members—have demonstrated changes in children’s brain function, using EEG to measure attention. Another example is the Baby’s First Years study, mentioned in the Explore activity above, which has provided preliminary data that increased income can change the brain. Babies from low income families that received high levels of monetary support showed greater high frequency neural activity, correlated with learning and the development of future cognitive skills, compared to the families that received low levels of monetary support. Simple interventions can make a difference too. Scientists have found that children who read books for fun, including those growing up in poverty, have larger cortical surface areas in several brain regions related to cognition and mental health. 

Image

Preliminary results from the Baby’s First Years study shows that infants from the high cash support group had higher levels of high frequency beta waves, which are associated with conscious thought and logical thinking later in life. Image adapted from Troller-Renfree et al, The impact of a poverty reduction intervention on infant brain activity. Image credit: Proc Natl Acad Sci U S A. 2022 Feb 1;119(5):e2115649119.

Teachers read the following information to help you frame the activity:
The following activity is adapted from the Baby Egg activity from the American Psychological Association. Students will be given the task of protecting an egg with available supplies they need to buy with a fixed income. They will relate this to socioeconomic status during reflection after the activity.

Use the following directions to guide students through the Baby Egg Activity:

1. Preparation: Be sure you have all necessary supplies:
   • 1 raw egg per group
   • Tickets or slips of paper
   • A garbage bag (for a drop location)
   • Protective materials: pieces of bubble wrap, padded mailers, newspaper sections, pieces of fabric, any other protective materials you want to include
2. Split students into three groups, A, B, and C, and give them a fixed amount of tickets (or slips of paper) they will use as money. Do not tell students how many tickets the other groups have yet.
   • Group A: 5 tickets
   • Group B: 10 tickets
   • Group C: 15 tickets
3. Give each group a raw egg to protect and some piece of masking tape.
4. Explain to students: Your goal is to purchase what you need to protect your egg from a fall. You may purchase the following materials:
   • Piece of bubble wrap: 5 tickets each
   • Padded mailer: 4 tickets each
   • Newspaper sections: 1 ticket each
   • Piece of fabric: 1 ticket each
     (could use other materials or any additional materials you want)
5. Allow the groups to come up to a material station to purchase protective material for their egg. Call group C first, then group B, and finally group A. 
6. Instruct all groups to protect their raw egg with their supplies from the market. 
7. Ask a representative from each group to stand on a chair with their wrapped egg and drop it onto the garbage bag.
8. Observe which eggs survived best.
9. Reveal to students how many tickets each group started with.
10. Explain the following to students and ask students to answer the reflection questions below:
    This activity was meant to model different socioeconomic groups and the advantages that some have over others when raising children. 
    • Which egg survived best? Why do you think that egg survived best?
    • What advantages did the “high socioeconomic status” group (group C, with the most tickets) have? What disadvantages did the lowest group (Group A with the least tickets) have?
    • Which group were you in and how did it make you feel when it was revealed that each group was given a different number of tickets to start?
    • How do you think this all applies to different socioeconomic groups? What disadvantages do low socioeconomic groups have when raising kids? How do you think this relates to trauma and stress response for children in low socioeconomic households?