In recent years, “slime” has become a big hit. You can find kits and recipes for it in craft stores, and we know lots of kids who have become expert slime artisans. Just for the record, we’ve been putting slime into baggies for kids to mix since we started Science in the Parks. We’d like to think we started the craze.

Here’s our own basic recipe. When we make this it includes hundreds of bags of the glue mix, along with a big container of the borax mix that we squirt into each scientist’s baggie:

• Mix 2 TABLEspoons (30 ml) of White Elmer’s Glue and 4 teaspoons (20 ml) of water (and food coloring if desired) in a plastic bag. Seal the bag and set it aside. This is a nice single-serving portion. Make as many bags as you will need in advance.
• Stir together 2/3 cup (160 ml) warm water and 1 teaspoon (5 ml) of Borax laundry booster (available with laundry products at many grocery stores) in a separate cup. The Borax should all dissolve in the water to make a solution. (From this solution you can make many bags of slime.)
• Add 4 teaspoons (20 ml) of the Borax solution to the plastic bag with the glue mix. Mix the ingredients around in the bag, and once it starts to all stick together, you can remove the “slime” from the bag and hold it in your hands. It will get less sticky as you continue to play with it.

Of course, an important feature of science and engineering is playing around with the variables. You can change any of these portions and see what happens. You’ll notice that our good friend at Georgia State University, “Dr. Science” (Brian Williams), along with his assistant and slime expert, Kaya, seems to just get a feel for the right proportions of ingredients. They give great explanations of what makes slime slimey. They also use a different glue than we do. It’s fun to compare!

Once you’ve made any slime or collection of different slimes, you could come up with your own questions and investigations:

• How long does it take take to drip? How would you measure this? Under what conditions? (Video can be a great way to record things so you can go back and measure times and distances really closely.)
• How fast does your slime ooze? Does it depend on how close together your fingers are? What else would it ooze through and how would that change the speed or other features of the oozing slime? (We have a lot of fun just typing “ooze” over and over.)
• How well does your slime stick? What things does it stick to? How do you even measure the stickiness?
• How does your slime respond to different temperatures?
• Does your slime bounce?
• How long does it take for the slime to go from a ball to a flat pancake?
• And on and on . . .

We get breathless just thinking about all the possibilities. Coming up with the question you want to ask and the way you want to study it is one of the most challenging and creative and important parts of doing science. Don’t be afraid to start by just playing.

Let us know what you find out if you have a chance!

By the way, we have our slime recipe along with lots of other “goo” recipes on this resource page. We’re sure you can find lots of others as well!