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Daily Do

Why Does the Cracker Taste Sweet?

Biology Crosscutting Concepts Disciplinary Core Ideas Is Lesson Plan Life Science NGSS Phenomena Physical Science 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 the cracker taste sweet?, students engage in science and engineering practices and use patterns as a thinking tool to make sense of the phenomenon of digestion. 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 middle school 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 the cracker taste sweet? Google slide presentation.

What phenomenon am I exploring today? (Introduce Phenomenon)

Begin by showing students slide 2. Say to students, "Imagine your family had a cookout for dinner. You decided to eat a hot dog in a bun and corn on the cob. Your dinner contains many different types of food molecules that your body uses in many different ways in a process called digestion. Both the bun and the corn contain a food molecule called carbohydrate. Our lesson today is going to focus on when we begin to digest carbohydrates."

Ask students to make a prediction and record it on their Student Handouts responding to the following question:

  • Which part of the digestive system do you think digestion of carbohydrates starts? Why?

Note: If students are unsure what is meant by digestion, share that when you say digestion you mean the process of breaking down food into substances that can be used by the body.

Accept all answers and let students know that today's lesson will explore different data to figure out if their predictions are correct.

Have students check their pantry to see if they have any saltine crackers and show slide 3. If they do not, don't worry, show the video linked on the slide. Tell students that as they chew, to notice what is happening to the taste of the cracker and record any observations on their Student Handouts.

Safety note: Crackers could be a choking hazard and students should be supervised while performing the experiment.

Ask students to share out what they noticed. Students may share the following:

  • The cracker gets real gummy and hard to chew.
  • The cracker starts to taste sweeter.

Transition students to thinking about what is happening to the cracker as they chew in terms of physical changes and chemical reactions. Show slide 4 and lead a discussion with students to identify their prior knowledge of these science ideas. Use the following prompts with students:

  • How do we describe a chemical reaction?
  • How do we describe physical changes?

Students may answer that in chemical reactions new substances are formed with properties that are different from the properties of the substances you started with. They may share a physical change is when we change something about a substance, maybe it's size, shape, or state of matter, but it's still the same substance. Students should have explored these ideas in 5th grade as well as in middle school. The depth of student answers may depend on their grade level and experiences in the middle school classroom.

Give students a few minutes to record their thoughts about what is happening to the cracker on question 3 in their Student Handouts. Have students share their claims about what is happening to the cracker. Let them know that we will be exploring data to gather evidence to support those claims in our next step.

Food Molecules

What does the data tell us? (Building Consensus)

Show slide 5 and allow students a few minutes to complete question 4 on their Student Handout.

  • If students are struggling to make sense of the data, explain to them that the light green bar is the food molecule in the graham cracker and the dark green bar is the food molecule in the graham cracker after it's been chewed in the mouth.

Show slide 6 and lead a discussion of what students noticed on the data. Use the following prompts:

  • What patterns did you notice in the data?
  • What conclusions can you make from the data?
  • What do you think is causing the changes we see in the data?

Students may identify that the glucose molecule increases and other complex carbohydrate molecule decreases. Some may further identify that they appear to increase and decrease by the same amount. Students may begin to conclude that other complex carbohydrates are turning into glucose in the mouth. They should begin to think that chemical changes, or reactions, are the only thing that can explain what is happening.

Say to students, "Now we have some data to let us know that there are some changes occurring in the mouth when we eat crackers. This is helping us support our earlier claims, but now we need some more information to see if our ideas about chemical reactions are correct."

Where is digestion starting? (Reading for Information)

Show slide 7 and tell students that you've found an article that might help us find some more evidence to support our claims. Give students time to read the article, "What's spit?", and answer questions 5 and 6 on their Student Handout.

Lead a discussion for students to share what scientific information they found in the article to help support their ideas about where digestion of carbohydrates begins. Students should share that spit contains amylase, an enzyme, that breaks down complex carbohydrates in the mouth. They should start to connect that this helps explain how the data shows that other complex carbohydrates decrease in the mouth while glucose increases. If students have completed the Daily Do Why does some food disappear? they may draw upon that lesson to make the connection that units of glucose join together to form other complex carbohydrates.

Summarize the discussion by saying, "So amylase helps break the larger complex carbohydrates into smaller pieces of glucose in the mouth. This must explain why we see the changes in the data and notice a sweet taste in our mouth."

What did we figure out? (Making Sense)

Transition to thinking about our predictions about where digestion of carbohydrates starts. Show slide 8 and give students a few minutes to answer question 7 on their Student Handouts. This question can be used as a formative assessment to check for student understanding. Allow students to share out their ideas and if their predictions were supported or refuted by what we've figured out today.

Students should identify that:

  • Digestion of carbohydrates begins in the mouth.
  • In our investigation, we noticed that the cracker began to taste sweet.
  • Data showed that the amount of other complex carbohydrates decreases and amount of glucose increases in the mouth.
  • The article told us that our spit, saliva, contains an enzyme that breaks down complex carbohydrates into smaller pieces, or glucose.

NSTA Collection of Resources for Today's Daily Do

NSTA has created a Why does the cracker taste sweet? 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 How do things inside our bodies work together to make us feel the way we do? storyline created by OpenSciEd. OpenSciEd is an open educational resource that can be used by parents and teachers to implement student-driven learning.

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