Students in grades 6 – 8 reinforce their knowledge of the human digestive system and explore the concepts of simulation and the engineering design process by developing a pill coating that can withstand the churning actions and acidic environment of the stomach. Teams test the coating’s durability by using a clear soda to simulate stomach acid.
Grade level: 6 -8
Time: 20 minutes for the digestion simulation, 50 minutes for the pill design.
- Define “simulation” and explain its importance in the science and engineering fields.
- Describe how simulation is used to test the human body’s reaction to medication.
- Describe the function of the stomach in the human digestion process.
- List several fluids our bodies use to digest food and understand how engineers simulate these fluids to perform experiments.
- Explain how engineers can directly and indirectly help people who are suffering from medical issues, specifically those relating to the digestive system.
- F. Manufacturing systems use mechanical processes that change the form of materials through the processes of separating, forming, combining, and conditioning them. [Grades 6 – 8]
- H. The manufacturing process includes the designing, development, making, and servicing of products and systems. [Grades 6 – 8]
- H. Biotechnology applies the principles of biology to create commercial products or processes. [Grades 6 – 8]
- G. A wide range of specialized equipment and practices is used to improve the production of food, fiber, fuel, and other useful products and in the care of animals. [Grades 6 – 8]
- Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred. [Grades 6-8]
- Define the criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions.
- Analyze data from tests to determine similarities and differences among several design solutions to identify the best characteristics of each that can be combined into a new solution to better meet the criteria for success.
- Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.
Common Core Mathematics Standards
- Understand the concept of a unit rate a/b associated with a ratio a:b, and use rate language in the context of a ratio relationship. For example, “This recipe has a ratio of 3 cups of flour to 4 cups of sugar, so there is 3/4 cup of flour for each cup of sugar.” [Grade 6]
- Develop a uniform probability model by assigning equal probability to all outcomes, and use the model to determine probabilities of events. [Grade 7]
Demonstration/Simulation of Digestion
Protect that Pill Activity
The design challenge.
Sarah is a fifth-grade student with an extremely sensitive stomach that is irritated by certain foods and many medications. She recently came down with an illness that caused a high fever, among other symptoms. Her mother wants to help fight the fever by giving Sarah some aspirin, but she is afraid that the medicine might make cause a stomach ache. Can you think of some ways you might be able to help Sarah?
(Possible answers: Have Sarah take the medication with food, use a different type of medication that does not cause stomach pain, use a coated aspirin, drink fluids and take a cooling sponge bath, have Sarah take the aspirin with another type of medication that helps stomach pain, etc.)
Before the Activity
- Gather materials and measure specified amounts of flour, corn starch, sugar and vegetable into individual bowls.
- Make enough copies of the Recipe and Fraction Worksheet to provide one per person.
- Divide the class into groups of two or three students each.
- Pass out worksheets and materials to each group (see Figure 1).
- Discuss with the class the different properties of each ingredient. Oil helps the dry ingredients stick together, helps make the mixture less sticky, and makes the coating less soluble. Flour and cornstarch are thickening agents with fairly similar properties. They also improve the workability of the overall mixture. Sugar thickens the mixture to some extent and makes the texture grainier, but can also make it less soluble when used in the right proportion, thereby improving its performance as a protective coating.
- Before any mixing is done, have student teams decide amongst themselves how much of each ingredient (in spoonfuls) they think they want in their coatings. These become their recipes, which they document on their worksheets.
- Following their recipes, direct students to begin mixing their coatings on paper plates (see Figure 1). If a team feels that more of a certain ingredient is called for, have them carefully measure it and add it into the mixture, remembering to make the changes to the recipe on their worksheets.
- When a group has finished creating their coating mixture and recipe, have them apply the coating to a piece of candy (see Figure 2). Encourage students to make a thin and sleek design so the pill is easy to swallow, inexpensive to ship, and requires less packaging.
Figure 2: Coated candy “pill” ready to test.
- When all of the groups are finished, have a representative from each bring their coated candy to the front of the class. For each team, fill a plastic glass half full with clear soda, plus one extra cup of clear soda for an uncoated piece of candy (so students can see their coatings’ effect on the dissolving rate of the candy). Label the cups with a marker so each group’s cup can be easily identified.
- With the timer read, at the same time have students drop their coated candies into their cups of clear soda while the teacher drops an uncoated candy into a cup of clear soda as a control (Figure 3).
- Allow the candy to sit in the soda for 10 minutes (see Figure 4). After several minutes, if the coatings do not look like they are dissolving, have one student from each group stir their coated candy in its soda cup until the 10 minutes is over. Ask students: How does this step simulates a pill going through the human digestive tract? (Answer: This simulates the acidic environment of the stomach, as well as its churning and agitating movement.) Why is it better to test the pill in a simulated environment rather than testing it on a human? (Possible answers: The coating could fail and make the person’s stomach hurt, it is easier to observe how the pill dissolves in the simulated environment, etc.).
- While waiting, keep students busy with another class activity or by having them draw ads that describe the benefits of their pill coatings.
- After 10 minutes have passed, have students remove their pieces of coated candy from the soda-filled cups (see Figure 5). As a class, make observations about which coating did the best job of protecting the candy “pill” and compare the coating recipes for each group to see what did and did not work. How did the coatings perform, compared to the uncoated control “pill,” and compared to the various team recipes?
- Have students calculate on their worksheets the fractions represented by each ingredient in their recipes. Compare recipes among teams, and discuss as a class, as described in the Assessment section. What are the relationships between performance and proportion of certain ingredients? What are the advantages and disadvantages of using certain materials?
- Using what they learned from analyzing the testing results and original recipes, direct each group to write down a new and improved coating recipe.
- Following their new recipes, have each team mix up a new coating batch. Do not allow them to make changes to their recipes during this stage.
- Repeat the same procedure for coating and testing, and then compare the results again as a class. What improvements were made?
- Conclude by reflecting on the activity in terms of the universal steps of the engineering design process: Ask, Imagine, Plan, Create and Improve, as described in the Assessment section. These are the steps engineers go through in designing new products and processes.
The activity materials have the potential to be extremely messy, so emphasize cleanliness and keep cleaning materials nearby. Consider laying down newspaper on and around the desks as protection from spills.
- To make very sticky concoctions more workable, add extra flour or corn starch.
- To prevent students from making a super-thick coating, set a limit on the maximum thickness permitted. Constraints like this are typical in real-world engineering design projects.
Activity Embedded Assessment
- Have students research the different materials used as pill coatings and the different mechanical systems used to coat pills.
- Redo the experiment and challenge the students to design their coatings based on taste, marketability, cost and ease of shipping and handling while still meeting a certain benchmark protection time (such as 10 minutes, 15 minutes, etc.) during the test phase.
- For lower grades, eliminate one or two of the dry ingredients to make the recipes simpler.
- For upper grades, add additional ingredients such as salt, corn syrup, or water to make the recipes more complex. Lead a discussion to explore why certain items were better pill coating ingredients than others and try to determine what function each ingredient served.
- For upper grades, turn this activity into a competition by challenging each group to make their pill dissolve at a specified time (that is, not too early and not too late).
Activity photos © 2008 Jacob Crosby, ITL Program, University of Colorado at Boulder.
Activities © 2008 by Regents of the University of Colorado; Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder.