Slime Shop: Engineer Your Own Slime
OverviewThere are many different ways to make slime. In this lesson plan, your students will use the engineering design process to design their own slime product. They will need to decide on the desired properties for their slime and then experiment to find the best recipe.
- Use the engineering design process to define criteria for creating slime
- Determine whether a new substance is formed by mixing other substances
NGSS AlignmentThis lesson helps students prepare for these Next Generation Science Standards Performance Expectations:
- 3-5-ETS1-1. Define a simple design problem reflecting a need or a want that includes specified criteria for success and constraints on materials, time, or cost.
- 5-PS1-4. Conduct an investigation to determine whether the mixing of two or more substances results in new substances.
- Optional: 5-PS1-2. Measure and graph quantities to provide evidence that regardless of the type of change that occurs when heating, cooling, or mixing substances, the total weight of matter is conserved. (see Variations)
|Science & Engineering Practices||Disciplinary Core Ideas||Crosscutting Concepts|
|Science & Engineering Practices||Constructing Explanations and Designing Solutions.
Generate and compare multiple solutions to a problem based on how well they meet the criteria and constraints of the design problem.
Planning and Carrying Out Investigations. Make observations and measurements to produce data to serve as the basis for evidence for an explanation of a phenomenon.
|Disciplinary Core Ideas||ETS1.A: Defining and Delimiting Engineering Problems.
Possible solutions to a problem are limited by available materials and resources (constraints). The success of a designed solution is determined by considering the desired features of a solution (criteria). Different proposals for solutions can be compared on the basis of how well each one meets the specified criteria for success or how well each takes the constraints into account.
PS1.B: Chemical Reactions. When two or more different substances are mixed, a new substance with different properties may be formed.
|Crosscutting Concepts||Stability and Change.
Change is measured in terms of differences over time and may occur at different rates.
For the main slime recipe, each group will need the following materials:
- Washable PVA school glue (like Elmer's®)
- Baking soda
- Contact lens solution (must contain both boric acid and sodium borate in ingredients)
- Food coloring
- Measuring spoons
- Measuring cup
- Mixing bowl
- Resealable plastic bags or food storage containers
- Cafeteria tray or other material to protect their work surface and make clean-up easier. Avoid porous materials like newspaper or cardboard, as they will absorb some of the slime.
You should also provide at least two additives that will allow students to change the properties of their slime:
- Glitter (sparkly slime)
- Iron filings (magnetic slime)
- Glow-in-the-dark paint (glow-in-the-dark slime)
- Thermochromic pigment (color-changing slime)
- Tonic water (glow-in-black-light slime)
- Foam shaving cream (fluffy slime)
Background Information for TeachersThis section contains a quick review for teachers of the science and concepts covered in this lesson.
"Slime" refers to a range of substances that you can buy or make yourself, like Gak™ or Silly Putty®. While their individual properties might vary slightly, in general, these substances are stretchy, gooey, sticky, or rubbery. Sometimes they might seem to behave like a solid; other times they might seem to behave more like a liquid.
Many slime recipes use glue and borax as the main ingredients. Glue is made of long, chain-shaped molecules called polymers. These molecules can easily slide over and around each other, kind of like the pasta in a pot of fresh-cooked spaghetti. This makes the glue very runny, which is why you can easily squeeze it out of a bottle. When mixed with borax*, the borate ions from the borax form weak bonds between the polymer chains in a process called crosslinking (Figure 1). This makes it more difficult for the polymer chains to slide around, making the glue less runny and more rubbery, forming slime. This reaction** results in an observable change in properties, as two different substances are combined to make a new substance with different properties. You can also add other ingredients to your slime to give it additional properties. For example, you can use iron filings to make magnetic slime.
Figure 1. Straight polymer chains (left) are linked together by borate to form a cross-linked polymer (right).
Given the range of available recipes and ingredients for slime, your students have a lot of choices if they want to make their own slime. In this project, they will think like chemical engineers and design their own slime. First, they will need to decide what properties they want their slime to have. What color should it be? Should it be runnier or thicker? Fluffy? Magnetic? Glow in the dark? Then, they will need to do some background research and experiment to find out what recipe gives them their desired properties.
* In this lesson plan, we recommend that you use contact lens solution to make slime. It contains other ingredients (boric acid and sodium borate) that cause a similar chemical reaction, but it is safer to handle than borax, which can cause skin irritation with excessive use.
** At this level, we do not make the distinction between chemical and physical reactions. It is not always possible to determine which is which using easily observable properties like color or texture changes.