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Daily Do

Why Does Some Food Disappear?

Biology Crosscutting Concepts Disciplinary Core Ideas Is Lesson Plan Life Science NGSS Phenomena Science and Engineering Practices Three-Dimensional Learning Middle School Grades 6-8

Welcome to NSTA's Daily Do

Teachers and families across the country are facing a new reality of providing opportunities for students to do science through distance and home learning. The Daily Do is one of the ways NSTA is supporting teachers and families with this endeavor. Each weekday, NSTA will share a sensemaking task teachers and families can use to engage their students in authentic, relevant science learning. We encourage families to make time for family science learning (science is a social process!) and are dedicated to helping students and their families find balance between learning science and the day-to-day responsibilities they have to stay healthy and safe.

Interested in learning about other ways NSTA is supporting teachers and families? Visit the NSTA homepage.

What is sensemaking?

Sensemaking is actively trying to figure out how the world works (science) or how to design solutions to problems (engineering). Students do science and engineering through the science and engineering practices. Engaging in these practices necessitates students be part of a learning community to be able to share ideas, evaluate competing ideas, give and receive critique, and reach consensus. Whether this community of learners is made up of classmates or family members, students and adults build and refine science and engineering knowledge together.


In today's Daily Do, Why does some food disappear?, students engage in science and engineering practices and use patterns as a thinking tool to make sense of the phenomenon of digesting a graham cracker. Students have an opportunity to apply physical science ideas about chemical reactions and physical changes to develop life science ideas about digestion (the beginning of the science idea the body is a system of multiple interacting systems). This task has been modified from its design to be used by students, families, and teachers in distance learning. While students could complete this task independently, we encourage students to work virtually with peers or in the home with family members.

Before you begin the task, you may want to access the accompanying Why does some food disappear? Google slide presentation.

Teaching this Daily Do: Together or Alone

Japan Dietary Life Rules

Why does some food disappear? is a stand-alone task. However, it can form the basis of an instructional sequence in which students coherently build science ideas about interacting body systems and physical change and chemical reactions.

The suggested order for this instructional sequence is Why does some food disappear? (this task), Why does the cracker taste sweet? and then Where does digestion occur?

As our collection of Daily Dos grows, you may find other ways to use this task to build a coherent instructional sequence for your students.

What phenomenon am I exploring today? (Introduce Phenomenon)

If they are available at home, have students grab a box of graham crackers. Otherwise, show Slide 2 and/or share the graham cracker student handout, and ask, "What types of food molecules are in a graham cracker?"

Students may identify what categories are listed in the nutritional label or list ingredients. If students list ingredients, ask, "How could we categorize those?" (fats, proteins, carbohydrates, etc.)

To motivate students to investigate what happens when they eat graham crackers, say, "I wonder what happens to all these molecules when we eat graham crackers. Does anyone have any ideas?" Accept all student ideas.

Show Slide 3 and tell students you are going to share food molecule data collected from the graham cracker (out of the box) and three parts of the digestive system - mouth, beginning of the small intestine, and large intestine (you may choose to point out these digestive system parts on the diagram). Share that students will use the Identify and Interpret, or I2 (I squared), data analysis strategy to help make sense of the data. Use Slide 4 to explain the strategy to students and then allow students to ask clarifying questions before moving onto data analysis.

Show Slide 5 and give students the Follow the Molecules student activity sheet. Help students orient themselves to the graph.

  • Ask, "Based on this graph, what food molecules make up an (uneaten) graham cracker?" This is denoted by the blue lines on the graph (water, protein, fats, glucose, other complex carbohydrates, and fiber).
  • Direct students' attention to the x-axis. Ask them to turn and talk with a partner and share ideas about what is meant by "relative amount." You might then ask students to share ideas and give an example from the graph. If students have a difficult time understanding what is meant by relative amount, you might ask, "How much more other complex carbohydrates are in a graham cracker relative to water?" (three times more) and "How much less protein is there relative to water?" (protein is about half the amount of water).
  • Support students in interpreting the other bars represented on the graph. Say, "Let's look at water. How does the amount of water molecules in an uneaten graham cracker compare to the amount of graham cracker water molecules in the mouth? (same amount) Beginning of small intestines? (same amount) Large intestines? (about half the number of original water molecules).

If students' productive struggle with the data is shifting toward frustration, go one step further:

  • "Take a look at AA, which stands for amino acids. How does the amount of AA molecules in the beginning of the small intestine compare to the amount in the uneaten graham cracker?" Students will notice there are no AA molecules in the uneaten graham cracker. You might say, "Where do you think the amino acids came from? Turn and talk with a partner." Students might say they think it used to be protein, fat and/or other complex carbohydrates because the amount of these food molecules in the beginning of the small intestine are lower than the amount of protein molecules in the uneaten graham cracker (conservation of matter.) Tell students to record their ideas in the I2 table on their handouts.

Allow students time to complete questions 1-2.

What does the data tell us? (Building Consensus)

Place students in small groups and then show slide 6. Ask students to first share with their group what they identified (what I see) and answer the following questions:

  • What are similarities and differences in your group's observations?
  • What pattern(s) in the data do you (the group) notice?

Next, ask students, still in their small groups, to interpret (what it means) the patterns they identified and to move toward reaching a group consensus.

  • How do you (the group) interpret these patterns?
  • What science ideas support your interpretation(s) of these patterns?
  • What ideas are you in agreement about?
  • What ideas are you NOT in agreement about?

Bring the class back together and engage the groups in a class consensus discussion. You might use the following prompts to help the class reach consensus:

  • What pattern(s) in the data did your group identify?
  • How did your group interpret this pattern?
  • Did another group notice the same pattern as _______'s group, but interpret it in a different way?
  • What ideas are we in agreement about?
  • Are there still places where we disagree? Can we clarify these?
  • Where should we go next to help us with areas where we are not sure/not in agreement?

Students will likely identify:

  • Amino acids (AA) and fatty acids are not present in the uneaten graham cracker but are found in the beginning of the small intestine.
  • Proteins, fatty acid, fats, glucose, and other complex carbohydrates are not found in the large intestine. (What happened to them?)
  • Some types of food molecules decrease from the mouth to large intestines and others increase.
  • The amount of fiber molecules did not change during digestion.
  • The amount of water molecules stayed the same in the mouth and beginning of small intestine and then decreased in the large intestine.

Students may interpret this as:

  • Our body digests (breaks down) proteins, fats, and other complex carbohydrates in the beginning of the small intestine.
  • Our body takes in food molecules (nutrients) in the small intestine and that's why they aren't found in the large intestine.

Students may ask:

  • Why does the amount of complex carbohydrates go down (decrease) in the mouth? Does that "count" as digestion?
  • How does the amount of glucose go up (increase) in the mouth?
  • Why can't our body digest fiber?
  • What is digestion?
  • Are there other kinds of food molecules that make up food?

You might say, "Many of us have questions about the carbohydrates - glucose, other complex carbohydrates, and fiber. Does it make sense to investigate these questions first?"

Why are some molecules disappearing and other's aren't? (Digging Deeper)

Show Slide 8 and tell students you found molecular models of glucose, starch (a complex carbohydrate), and fiber that might help explain why some of the carbohydrate amounts change (glucose and other complex carbohydrates) and fiber does not.

Ask students to turn to a partner and share what they have heard about these types of food molecules. Students may know that some foods, like bread or potatoes, contain a lot of starch; bread and pasta are high in carbohydrates, and/or fiber helps make you poop. Others may know that glucose is something that diabetics monitor and eating sugary foods or foods high in carbohydrates makes the amount of glucose in their (diabetics') blood increase.

Show slide 8 and share the Molecule Structure student activity sheet with students. Give students independent thinking time to observe the molecule structures and record similarities and differences between them. Then, assign students to small groups and ask them to share the similarities and differences they identified.

Bring students back together and ask them to share similarities and difference with the class. Students will likely identify the following similarities and differences:

  • All three molecules are made of the same atoms - carbon, hydrogen, and oxygen
  • Glucose is the smallest molecule and fiber is the biggest molecule
  • Starch and fiber look like they are made of many glucose molecules connected together.

What did we figure out? (Making Sense)

Show Slide 9 and lead a building understanding discussion using the prompt: How could the structure of the different carbohydrates explain why some carbohydrates are digested (broken down) and others are not? You might use some of the following prompts to facilitate the discussion:

  • What are some of your claims?
  • What's your evidence? (or Does anyone have any evidence to support Group A's claim?)
  • ___and ___ , you made similar claims. Did you have the same evidence?
  • What can we conclude?
  • What else do we need to find out? What might we do next?

Students may say the large size of a fiber molecule might explain why our body's digestive system can't digest (break down) the fiber. Other students may focus on the smaller-sized glucose and starch molecules and say because they are smaller our digestive system has an easier time digesting them (breaking them down).

Ask students, "What else do we need to find out?" Students will likely say we need to figure out how molecules break down. (If students don't say this you might ask, "What does 'digestion' mean?" or "What do we mean when we say 'break down'?")

Consider navigating students to the Daily Do Why does the cracker taste sweet? to begin to answer this question.

NSTA Collection of Resources for Today's Daily Do

NSTA has created a Why does some food disappear? collection of resources to support teachers and families using this task. If you're an NSTA member, you can add this collection to your library by clicking ADD TO MY LIBRARY located near the top of the page (at right in the blue box).

Check Out Previous Daily Dos from NSTA

The NSTA Daily Do is an open educational resource (OER) and can be used by educators and families providing students distance and home science learning. Access the entire collection of NSTA Daily Dos.


This Daily Do is inspired and uses materials from the OpenSciEd Metabolic Reactions unit titled How do things inside our bodies work together to make us feel the way we do? OpenSciEd is an open educational resource that can be used by parents and teachers to implement student-driven learning.

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