SHPE Foundation SHPE Jr. Chapter Curriculum Hands-on Activity Training TeachEngineering Hands-on Activity: * Creepy Silly Putty TeachEngineering Digital Library: teachengineering.org _surg/cub_surg_lesson04_activity1.xml

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General Advice Be prepared! Do each activity beforehand Make sure all materials are available Keep students on task Follow the time frame Be flexible Have Fun!! SHPE Foundation SHPE Jr. Chapter Curriculum Hands-On Activity Training

Creepy Silly Putty Material behavior and properties Engineering focus: o Engineering Research/Analysis Students learn about viscoelastic material behavior, such as strain rate dependence and creep, by using silly putty, an easy-to-make polymer material. By seeing the viscoelastic behavior of silly putty, students start to gain an understanding of how biological materials function. Learning objectives: o Demonstrate two viscoelastic material behaviors (strain rate dependence and creep) with silly putty. o Explain the effects of borax concentration on the material properties of silly putty. o Explain sources of error in experimental data. o Graph collected data using Microsoft Excel. (optional) SHPE Foundation SHPE Jr. Chapter Curriculum Hands-On Activity Training Full Activity on TeachEngineering

Creepy Silly Putty Suggested time: 60 minutes Suggested group size: 3 students/group Materials o Each group needs: 2 plastic containers, for mixing water and glue, and water and borax powder (such as GladWare tall square or deep dish plastic containers, ~ 6 x 11 x 5-in and 6 x 9 x 7-in [L x W x H]; no lids needed) 3 disposable spoons 3 plastic bags that seal (such as Ziploc sandwich bags) 2 ounce (1/4 cup) measuring cup for fluids ($1 at Dollar stores) ruler stopwatch white school glue, 6 ounces marker, to label plastic bags soap and water, for cleaning containers and hands (optional) Creepy Silly Putty Data Analysis Worksheet, one per studentCreepy Silly Putty Data Analysis Worksheet o To share with the class: borax, 76-ounce box (aka sodium borate; available at grocery stores) 1 set of measuring spoons for solids ($1 at Dollar stores) (optional) computer and projector to show the Making Silly Putty Instructions and Creepy Silly Putty Experiment Instructions PowerPoint filesMaking Silly Putty InstructionsCreepy Silly Putty Experiment Instructions SHPE Foundation SHPE Jr. Chapter Curriculum Hands-On Activity Training ng.org/view_activity.php?u rl=collection/cub_/activities/ cub_surg/cub_surg_lesson0 4_activity1.xml

Creepy Silly Putty SHPE Foundation SHPE Jr. Chapter Curriculum Hands-On Activity Training Engineering Connection (Real World Application): Bioengineering/Biomedical engineering Bioengineers are engineers who study biological materials and how they function in healthy and diseased states. Since biological materials exhibit viscoelastic behavior, engineers must understand this behavior in order to fully characterize these materials. Engineers may also design devices that come into contact with biological materials. So, to ensure effective and successful device performance, engineers must understand how the biological environment reacts to the forces that a device imposes. Polymers such as silly putty also exhibit viscoelastic behavior and can be used to demonstrate and learn about the functioning of biological materials.

Creepy Silly Putty SHPE Foundation SHPE Jr. Chapter Curriculum Hands-On Activity Training Engineering Connection (cont.): Silly putty can also be used to learn about and analyze creep (deformation), which is a concern in other areas of engineering, including civil engineering, structural engineering, and mechanical engineering Engineers who design and construct technologies such as nuclear power plants and jet engines must consider the effects of creep _nuclear.html

Creepy Silly Putty SHPE Foundation SHPE Jr. Chapter Curriculum Hands-On Activity Training Vocabulary TermsDefinitions/Equations elasticity When a material instantaneously returns to its original shape after a force is removed. viscosity A measure of a fluid’s resistance to deformation. (For example, honey is more viscous than water.) viscoelasticity When a material exhibits both viscous and elastic characteristics when undergoing deformation. creep (deformation) When a solid material moves slowly or deforms due to heat or a force. strain rate Rate of change in strain (deformation) of a material. (How fast the material creeps/deforms.) polymer A large molecule made up of repeating subunits. Biomaterials, such as DNA and proteins, as well as synthetic materials, including many plastics (styrofoam) are examples of polymers. Polymers exhibit viscoelasticity.

Creepy Silly Putty SHPE Foundation SHPE Jr. Chapter Curriculum Hands-On Activity Training Activity Procedure: Part 1 – Making and Playing with Silly Putty 1.Have each group collect two containers, three spoons and three plastic bags. 2.In one container, mix 1 ounce warm water with ¼ teaspoon borax. 3.In the other container, mix together 2 ounces glue and 2 ounces warm water until you have a uniform consistency and color. (It is important that this solution be uniform, with no areas of excess water, or it prolongs the mixing time in step 5.) 4.While stirring, slowly pour the borax mixture into the glue mixture. Be sure that all of the borax is transferred into the glue solution. 5.When the solution starts to thicken, mix with your hands instead of the spoon. Continue to mix until a uniform solution is achieved and NO water is present.

Creepy Silly Putty SHPE Foundation SHPE Jr. Chapter Curriculum Hands-On Activity Training Activity Procedure (cont.): 6.Store in a plastic bag labeled: “low concentration”. 7.Thoroughly clean both containers and discard the spoon. 8.Repeat steps 2–7 two more times, with 1 teaspoon borax (“medium concentration”) and 2 teaspoons borax (“high concentration”), respectively. 9.Make sure all bags are labeled with the concentration level and your team name. 10.Play: Encourage students to explore the unique properties of silly putty (viscoelastic behavior) and note the comparative differences in responses to force by each batch. (For example: Stretch the silly putty at different rates, roll the silly putty into balls and let it sit on a table, and form each batch into a cylinder shape and hold one end of it, etc. Tip: While exploring the silly putty properties, be careful not to mix up the different batches or lose track of the borax concentration of each batch since teams will need to know this for Part 2 of the activity.)

Creepy Silly Putty SHPE Foundation SHPE Jr. Chapter Curriculum Hands-On Activity Training Activity Procedure (cont.): 11.Have students share and discuss their observations as they pertain to materials behavior. Does silly putty behave like an elastic solid or a viscous fluid? Expected observations: o If you slowly stretch the silly putty, it is very pliable and seems to stretch forever; it behaves like a viscous fluid. o If you quickly stretch the silly putty, then it breaks immediately, seems stiff, and behaves like a solid with little elasticity. o The same material has two very different responses to a force depending on how fast the force was applied. o Over time, the balls of silly putty on the tabletop deform and spread out, like a viscous fluid. o However, you can hold the silly putty without a container and use your hands to deform it into different shapes, like a solid. o While holding a cylinder of silly putty by one end, the silly putty slowly stretches and elongates from its own weight. o So, silly putty behaves like an elastic solid and a viscous fluid depending on the forces that are applied to it. Exhibiting both characteristics is the definition of a viscoelastic material.

Creepy Silly Putty SHPE Foundation SHPE Jr. Chapter Curriculum Hands-On Activity Training Activity Procedure: Part 2 – Silly Putting Experimentation and Testing 1.Have each group collect the bags of silly putty that students made in Part 1 (all 3 borax concentrations), a ruler and a stopwatch. Assign students the following specific group roles to perform during the experiment and data gathering: 1 person forms and holds the silly putty at the same height 1 person holds the ruler and checks initial placement of the silly putty 1 person operates the stopwatch 1 person records data (if groups of three, assign this fourth role to everyone) 2.Form the silly putty into a cylinder with a diameter of approximately 1.5 inches. (It is very important that the diameter and shape of the silly putty be consistent for each trial.) 3.Hold the ruler vertically so that the "0 inches" mark touches the table. 4.Hold the top end of the silly putty cylinder so that the bottom of the silly putty cylinder is positioned 6 inches above the table. 5.Immediately start the stopwatch. Keep the hand holding the silly putty stationary and at the same height until the silly putty touches the table.

Creepy Silly Putty SHPE Foundation SHPE Jr. Chapter Curriculum Hands-On Activity Training Activity Procedure (cont.): 6.Record the amount of time it takes for the silly putty to touch the table. 7.Repeat steps 2–6 with the same silly putty batch two more times, recording the times. 8.Complete steps 2–7 for each silly putty concentration. (Expect students to notice that as the concentration of borax increases, the amount of time for the silly putty to creep 6 inches also increases. If students obtain questionable results, run more trials and throw out bad data.) 9.Have students reflect on the data they collected by asking them the questions in the Assessment section (next slide). Discuss as a class or assign students to write down their own answers 10.(optional) Conclude by handing out the worksheets for students to complete and hand in.

Creepy Silly Putty SHPE Foundation SHPE Jr. Chapter Curriculum Hands-On Activity Training Assessments: Before the Activity: o Questions & Predictions: Today you will make silly putty by mixing together glue, water and borax. What do you think the borax does to the glue to form silly putty? Record your hypothesis. Your group will make three batches, each with different concentrations of borax (high, medium and low concentrations). Write your predictions of how you think the different borax concentrations will affect the silly putty: How will the material properties change? Which concentration do you think will be easiest to make?

Creepy Silly Putty SHPE Foundation SHPE Jr. Chapter Curriculum Hands-On Activity Training Assessments (cont.): After Part 1: o Revisit Predictions: Have students revisit their earlier predictions. Discuss as a class or assign students to write down their own answers. Ask the students: Was your hypothesis correct about how the borax concentrations changed the material properties of the silly putty? Explain. (As the concentration of borax increases, the amount of time for the silly putty to creep 6 inches also increases.) Did you see any differences while making the three concentrations? Is silly putty an elastic solid or a viscous fluid. Which one? Why? (Silly putty is both!)

Creepy Silly Putty SHPE Foundation SHPE Jr. Chapter Curriculum Hands-On Activity Training Assessments (cont.): After Part 2: o Data Reflection: Have students reflect on the data they collected and answer the following questions. Did you have any variations in the time it took for the silly putty to creep 6 inches when you repeated the experiment for the same concentration? (Expect students to say yes.) If so, what factors could have caused this? (Possible answers: Human variability and error, for example, if the silly putty is not formed into a uniform cross section cylinder, held in the same way for every trial, and held at the same height while it is deforming.) Why do you think the concentration of borax altered the viscoelastic properties of silly putty? (At this time, just have students predict why they think borax is altering the properties of the silly putty. The answer will be revealed to the students and discussed in more detail during the lesson. Answer: Glue is a polymer, so on a molecular level it consists of strings of compounds, similar to a plate of spaghetti. Borax reacts with the glue and binds the strings together [cross-linking], similar to when a plate of spaghetti starts to dry and all the noodles stick to each other. The more borax you add to the glue, the more cross-links that form, resulting in a stiffer material.)

Creepy Silly Putty SHPE Foundation SHPE Jr. Chapter Curriculum Hands-On Activity Training Teaching tips: o Emphasize the science concepts, vocabulary, and engineering connection; reinforce these throughout the activity. o Part 2 works best when specific team jobs are assigned to students at the beginning of the activity and not varied throughout the activity. o Part 2 of this activity is very sensitive to human variability and error. The force driving the creep behavior is the weight of the silly putty. If the silly putty is not formed into a uniform cross section cylinder and held in the same way for every trial, the results will have a lot of variability and error. If students obtain questionable results, run more trials and throw out bad data. o Have fun and encourage students to have fun!!

Activity Takeaways Teambuilding skills o Making decisions, sharing tasks and materials Engineering skills o Engineering Research and Analysis : creating silly putty by following a formula, taking quantitative measurements, analyzing results, relating results to real world problems and technologies. SHPE Foundation SHPE Jr. Chapter Curriculum Hands-On Activity Training Encouragement through hands- on learning o This activity is very hands-on, and couples “playing” with data collection and analysis. Motivation through having fun o Introduce the activity as a fun learning experience!

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