Grade Level: Middle school; also scalable for elementary school
Time Required: 1 hours 30 minutes (wild guess!)
Maker Challenge Recap
Students become product engineers in a bouncy ball factory as they design and prototype a polymer bouncy ball that meets specific requirements: must be spherical in shape, cannot disintegrate when thrown on the ground, and, of course, must bounce. Along with these design elements, students can build (with teacher assistance) a “shadow box” that helps measure the contact angle of the polymer that provides data on how to iterate. In addition, students must consider the aesthetics of their bouncy balls for customer approval and marketing purposes. Using the engineering design process, students design and create bouncy balls from polymers to create a fun, exciting toy for children.
- glue (such as an Elmer’s glue-all or school glue product)
- beakers or other glassware for mixing ingredients
- measuring spoons
- digital scale
- heat source (to heat the water)
- UV light bulb
- cardboard box, 25 cm x 25 cm (~10 in x 10 in)
- ultraviolet light sensitive paper (SunPrint Paper, for instance) 3 sheets per group
- notebook paper
- food coloring or glitter (optional, but helps make the slime more vibrant)
- Experiment Recording Worksheet
Worksheets and AttachmentsVisit [ ] to print or download.
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More Curriculum Like This
Students explore the basic characteristics of polymers through the introduction of two polymer categories: thermoplastics and thermosets. During teacher demos, students observe the unique behaviors of thermoplastics.
Have you ever made slime in your science class? What can you tell me about slime? (Listen to students answers.) The slime you made is your science class is an example of a polymer. Does anyone know what a polymer is? (Listen to students answers.) Polymers are substances made by linking together chains of similar bonded units. Bouncy balls are also made from polymers.
Does anyone know what a mixture is? (Listen to student answers.) Mixtures are any combination of two or more items and can be made with solids, liquids or gases. Any combination will result in a mixture. Sometimes the two or more ingredients look all the same when mixed together and sometimes they do not. Did you know that we could make bouncy balls using the same ingredients that we used to make slime? I know that when we heat up water and dissolve borax into the water, the mixture forms long chains of polymers that are too tiny to see with our eyes. After we add the glue, the glue helps bind the long chains together and we get a very slippery, slimy substance that can bounce if the conditions are just right!
I want to make a bouncy ball factory, and you are going to help me create the formula to use in the creation of these bouncy balls. I made a formula, but I am not sure if my balls will bounce so let us see what happens.
[Teacher combines 120 ml (4 oz.) of glue and 175 ml (6 oz.) of warm water in a clean beaker and mixes them together. In a second beaker, the teacher makes a solution of one teaspoon Borax and 120 ml (½ cup) of water. After the borax dissolves, combine the glue-water solution with the borax-water solution and mix. The combined solutions should start to form a kind of slime. Remove this slime from the beaker.]
If the product is too watery it will not bounce when I drop it onto the floor, instead it will splat onto the floor. If the mixture is too dry, the polymer will look like scrambled eggs and break apart on the floor. You have to find a good balance between wet and dry, and we can actually measure this using a technique called “contact angle”! Let us use the cardboard box, light-sensitive paper, and light bulb and work to build a shadow box that we can use for our measurements and iteration!
[After students construct the shadow box, the teacher takes the watery slime out of the beaker and shows how it resembles more of a blob than a ball. The teacher shows the angle of the base compared to the hump of the blob using the shadow box with the UV light. It will resemble a hill, when we want it to look more like a ball as shown by the UV sensitive paper.]
[The teacher demonstrates how ineffective this mixture is at being a bouncy ball by splatting it onto a hard surface like a linoleum floor or a countertop.]
Oh, no! It seems like my formula does not make a very good bouncy ball. Good thing I have a room full of engineers ready to help me by using the engineering design process! Use the Engineering Design Process Notebook to document your engineering work!
You will now get to make your own bouncy ball from only get three ingredients: borax, glue, and water. You will have to be very precise in your measurements, and you will probably have a few failures along the way but keep trying!
You must conduct at least three experiments on three different products. Make sure to record exactly how much of each ingredient you used, your contact angle, if it bounced, and if it failed in some way. Be descriptive when it fails, because you can use that experience to help you find the right balance of materials next time!
- Refer to the Engineering Design Process hub on TeachEngineering to guide your students through the challenge.
- As needed, utilize the Engineering Design Process Notebook for engineering process documentation.
- Show students this YouTube video, How to Make Slime with Borax and Glue that offers an overview of the process.
- Have the students organize themselves into groups of three, or organize the class into groups based on different skill levels and abilities, if desired.
- Tell students to confer and then decide on a starting ratio of materials for their bouncy ball.
- Instruct them to make their product and test it for shape, pliability, bounciness, and aesthetics.
- Remind students that the goal is to find the right ratio of materials, and when they experiment to write down everything that happens so others can learn from the mistakes.
- Students should be free to see what other groups are doing and to collaborate with their peers.
- Students should record their progress using the Experiment Recording Worksheet.
If students need help, you can say the following:
- How firm is a bouncy ball from the store?
- Did the wet slime bounce very well? If not, how can we change the formula to make it different?
- What happens when a bouncy ball is too dry?
- What are the other groups around you doing, and have they been successful?
- Are there other substances we could add to change the consistency of the ball?
As a class, have the students discuss what worked and what did not work:
- What happened when you tested your experiments? What did not work very well? What did work well?
- Did the contact angle measurements help? What was the contact angle of the best bouncy ball? What is the contact angle of your second best bouncy ball?
- What lessons did you learn from the failed experiments?
- What did your group learn from what other groups were doing? Did you use any of these ideas?
- What materials would you add to your experiments to make your bouncy balls even better?
- What extra materials would you add to your formula to make the bouncy balls more appealing to your audience?
After the discussion, write the best student formula on the board and then have the students write the winning formula in their journals so everyone can share in the success.
During the maker time, instructors should walk the room and ask students questions such as:
- What kind of properties are you looking for in your bouncy ball?
- What happened in your last experiment? What worked? What did not work? What are you going to change or modify to make your product better?
- Would a younger kid have fun playing with your product?
- What kind of colors could you give your product to make it eye catching?
Copyright© 2019 by Regents of the University of Colorado; original © 2019 Rice University
ContributorsZachary A. Hilburn
Supporting ProgramNanotechnology RET, Department of Earth Science, School Science and Technology, Rice University
This material was developed based upon work supported by the National Science Foundation under grant no. EEC 1406885—the Nanotechnology Research Experience for Teachers at the Rice University School Science and Technology in Houston, TX. Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.
Last modified: October 21, 2020