Slime Science Project: Investigating the Science of Slime

Slime might make a mess, but did you know that slime makes a perfect science fair project?!?  Not only can you test various chemistry and physics hypotheses, your kids can also have fun and finish it IN JUST A WEEKEND!!  For all those parents out there frantically heading into the last days/hours before the science fair, this is your winner!  Our slime science project outlined below walks you through the potential setup from start to finish.  It’s one of many!!  While you could get adventurous and try working with more elaborate slime recipes (e.g. magnetic slime, glow slime), even our basic recipe can get you a cool slime science project addressing all the requirements of any science fair.  Let’s science!

Slime Science Project:  An Overview

Below, we outline a few simple experiments to assess different physical properties associated with slime.  But first, we delve more into the science behind slime.  To be honest, there are truly a TON of directions you can go with this project and the fact that it can be completed in a weekend makes it a great last minute science fair project!

Now, for an easy to read, step-by-step guide about making slime, please be sure to look at our How to Make Slime: The Ultimate Guide post.  In that guide, we outline various slime recipes and walk through how to make slime.  If you encounter issues in this science fair project, be sure to reference back to that post.

Science of Slime – How Chemistry Affects Physical Properties of Slime

Like our other projects, this slime science project starts with a question.  One that comes up often when kids first make slime is “how does slime actually get to be slime”?   In other words, how does it go from sticky to gooey?  Our slime science project introduces kids to CROSSLINKING and how the PHYSICAL properties of slime change depending on the type of CHEMICAL REACTIONS we use in our slime prep process.

Can’t we just make the slime and call it a day?  Sure, you totally can and feel free!  However, if you want the kiddos to get familiar with the scientific method (e.g hypothesis generation, experiment design), then read on.  Also, if you have a science fair coming up, this is a great project that can be tackled in a weekend from start to finish.

Background:  The Science of Slime

What is slime?  It’s not a liquid, but it’s not a solid either.  So, what the heck is slime anyway??  Well, if I ask the kids, they tell me it’s a gooey, squishy “thing”.  If you’ve ever tried to explain states of matter to kids (e.g. solid vs. liquid vs. gas), slime always throws them for a loop.  Beyond being a bit of a ‘tweener, slime is a great way to teach kids about how chemical reactions can change physical properties.

So, what is actually happening when we make slime?  Ok.  If I’m losing you at the word chemical reactions, don’t worry.  When we make slime, we take a polymer and link the molecules together.  In the experiment below, our polymer will be white glue.  The glue consists of a collection of POLYVINYL ACETATE (PVA) molecules (see picture below).  We will also be using Borax laundry detergent as our SLIME ACTIVATOR.

What’s so magical about Borax?  Well, it happens to contain borate ions (see the picture below – that B with the four arms).  When you mix Borax and glue, the borate ions start to “hold hands” with the PVA chains in the glue.  The dotted lines and solid lines below represent CHEMICAL BONDS.  These bonds are strong!  This means it’s hard to separate the glue from the borate.  If you use too much Borax in your slime, you can imagine a lot of kids grabbing on to each other.  Impossible to get through and hard to move.  Same thing with slime.  You will likely get brittle, inflexible material.

With this in mind, our experiment is going to evaluate how CROSSLINKING can effect the stretchiness of our slime.  Another word to introduce the kiddos to is VISCOSITY.  In simple terms, viscosity is kind of like how “thick” a fluid may be.  Compare honey and water – which one would be more viscous?  How could you test viscosity?

Who can do this science fair project?  3rd grade and up

We’ve done the slime making with students as young as preschool.  However, some of the concepts might be tricky to grasp for younger kids.

Materials – What you need for the experiment

As always, before you begin your experiment, you want to make sure you have all of your materials.  Below are the basic materials for your slime science project.  If you run into trouble, please see our Ultimate Guide on How To Make Slime for more details.

• Mixing containers (old bowls, paper/plastic bowls).  We use these to mix and prepare our slime.
• Mixing sticks (popsicle sticks).  Same thing – mixing slime gets messy, so if you prefer to use popsicle sticks this will help.
• Elmer’s school glue (the white kind – here’s what we use).  Glue = critical reagent!  This represents our polymer.
• Borax laundry detergent (the powder kind).  See the picture at the right; as long as the detergent contains sodium borate, that is most important.
• Water.  For mixing with the glue, borax and clean up.
• Timer.  We will use for a few things.
• Funnel.  Pouring liquids through a funnel is one way to measure viscosity – we will use it for our slime!
• Tape measure.  For stretching out and measuring how “gooey” the slimes turn out.
• Lotion (whatever you have in the house).  This is an oil that we are adding.
• Paper / pencil / camera.  Always be sure to record the data!

Designing the experiment:  picking a hypothesis

Before we get our hands wet (ha!), we need to think about our experimental design.  If you’ve read through some of our other experiments (germiest spot in school), then you might remember that a HYPOTHESIS is essentially a guess about what you think will happen in the experiment.  There are literally dozens of experiments you can do with slime – which makes it so great – but it can also be hard for kiddos to narrow it down.  In this case, since we’ve had our kids ask questions about the “gooey”-ness of slime, we thought it would be interesting to see how stretchy our slime can be, using different amounts of Borax.

Our Hypothesis

Our hypothesis here will be that too much Borax will make slime that isn’t very gooey.  How will we test our hypothesis?  Let’s use viscosity!  We will measure how viscous the slimes are that we make.

Experimental controls

At this point, we’ll also want to pick out some “controls” to include in our experiment (QUICK question for the kiddos:  why is this important?  A:  to make sure our experiment is testing what we think it’s testing).  We need a POSITIVE and a NEGATIVE control.  A good NEGATIVE control would not add any Borax at all to the mix – this won’t be gooey.  A good POSITIVE control would add Borax to ensure crosslinking occurs.  Any other ideas?

Methods/Procedure – How We Will Finish Our Slime Science Project:

For our slime science project, we will be examining the impact of crosslinking on slime viscosity.  In other words, we will be adding varying amounts of Borax to our slime to see how it impacts the “stretchiness” of our slime.  We will also incorporate another ingredient (lotion) to see if we can counteract the effects of too much crosslinking.  While you’re on your own with the science fair project board, there should be enough info to make your own.  How long this will take you from start to finish?  Assume about 30 minutes of setup/prep time, about 1 hour for making slime/testing, and 1 hour to analyze.

Setting up your materials

Before you get started, make sure you have plenty of disposable bowls and mixing sticks… while you can use non-disposable items, this makes cleanup a little faster/easier.  We also want to organize the VARIABLES in our experiment.  The table below illustrates the different conditions we tested.  We will make seven different slime batches to COMPARE the different conditions.  Additionally, you can make duplicates for each set of conditions if working with a partner.

#1 acts as our NEGATIVE control.  Without Borax, we just have glue and water.  #2-#5 test how changes in the Borax amount effect viscosity and stretchiness.  #6 and #7 are an EXTRA experiment that adds lotion to see how it influences viscosity.  If you have different ingredients you’d like to try, give it a go!  As you set up materials, label the different bowls so you remember which condition you are testing.

Make sure the kiddos GUESS / HYPOTHESIZE which slime will be the stretchiest and which will be the most viscous.  Without further ado….  let’s make slime!

Making the slime

PROCEDURE:

1. Prepare the Borax solution.   First, dissolve 1 teaspoon of Borax detergent in 1 cup of warm water.  Mix until everything disappears, then set the solution to the side – we won’t use it until we’ve mixed our glue/water solution in step #3.
2. Prepare the glue.  Next, in the different containers, add the correct amount of glue to each container.  Pour in the appropriate amount of water.  Ideally, we are sticking with a 1:1 ratio of glue:water.  COULD YOU TEST THIS VARIABLE?  Absolutely!!!
3. Mix the glue/water.   BE WARNED:  You will probably get messy. Stir vigorously to get the water/glue mixed up.  You can add a few drops of food coloring or glitter if you’d like.  Also, mixing can be done with a spoon at this point – our favorite approach uses paper bowls and plastic spoons or popsicle sticks to stir.
4. Add Borax solution.  At this point, you will want to add the correct amount of Borax solution to each bowl.  This solution is what we prepared in the first step.  Remember, this step CROSSLINKS the glue molecules…  it goes from sticky to gooey.  You can mix with your hands or a spoon.  SUGGESTION:  only add a small amount of borax at a time – mix – then add more.  Whatever you do, try to be consistent across the different batches.
5. Kneed it/mix it. Keep stirring as you add the Borax solution.  When the slime is starting to come together, you’ll need to start mixing with your hands.  RECORD your observations for each batch – how does it feel?  Do some combinations mix better/easier than others?  When done with mixing, you’re ready to begin testing it.  If you are using #6 and #7, now is the time to mix in the lotion.
6. Clean up.  Word of warning – do not pour slime components down the drain.  You risk the material solidifying or getting stuck in your pipes.  Wrap up waste and throw out in trash.

Testing the slime

Testing viscosity of solutions isn’t as hard as it sounds.  One trick uses a cylinder filled with the fluid.  A ball bearing is dropped in the fluid and timed to see how long it takes to go from the drop to the bottom.  Solutions with higher viscosity means it takes longer for the bearing to reach the bottom.  If you don’t have a cylinder handy, an alternative is pouring the solution through a funnel with a small opening.  Same concept – fluids with higher viscosity take longer to pour through the funnel.

At this stage, record how long it takes for the different slimes to flow through the funnel.

How else can we test the slime?  You can also try to see how far the slimes pull.  This uses the tape measure.  First, have one person hold the slime at a “starting point”.  Using paper and your tape measure/ruler, measure how long the slime pulls without pulling apart.  Don’t forget to take pictures!  Are there other tests you can think of to compare the slimes?

Results – Data Analysis

You made it!  Way to go!!   If you’ve finished all seven slimes and testing, the kiddos have a lot of data to sift through.  Using the prior table, you can easily record the results of the tests (see below).

Was the hypothesis proven?

Conclusions:  Did your slime science project work?

Wow!  Another great experiment under the belt!  If things didn’t work out like you thought they would, what do you think could be some good explanations?  What would you do differently?  Could other variables be important — like temperature?  What about the brand of the reagents?  Like I said in the beginning, there’s literally a 100 different experiments you can come up with slime!

What were we surprised about?  Well, the kiddos were surprised that it “worked”.  🙂  While I’m happy that things came together, there was still troubleshooting that had to be done.  They want to make more slimes – but different variations beyond what we did here.  How did your project pan out?  We love to see science fair projects and the slime science project is no exception – feel free to share those boards!