This is a classic experiment in colloids.
Goo Recipe:
1 cup cornstarch
1/2 cup water
Food color
1. Pour corn starch into a mixing bowl.
2. Pour water into cornstarch. You can add the food color into the water, or for mixing fun add it into the mixture after mixing.
3. Mix together with your hands!
4. Have fun!
Brianna poured it the cornstarch into the bowl. At this point she felt the cornstarch to see what it felt like. I explained what cornstarch was and how it is used to thicken sauces. I also asked her to make a prediction on what would happen. Her hypothesis was it would get thicker.
As she was mixing it she realized it was thicker, but also kind of weird. We had an extra cup of water and some napkins handy to clean our hands if needed.
It got thicker and would run like goo, but also got very hard if you moved it too quickly.
First, I had Brianna poke the water in our cup to see how it reacted when she poked it fast and then again when slow. With the water the biggest difference was if you poked it slow the water was more calm than if you poked it fast and it splashed.
I then had her poke the goo quickly and none of it got on her finger. It became a solid when she poked it fast. However, if she poked it slowly her fingers sank like it was liquid, and in turn got covered in goo!
I then explained to her why this happened.
EXPLAINATION:
This mixture is called a colloid. A colloid is a when the solid particles, or tiny pieces, of a substance are suspended, or floating, in another substance. The mixture became hard because when moving through it quickly the particles collide with each other and cause a back up. When you move through it slowly the particles have time to readjust and move more smoothly. It's state of being is pressure sensitive; solid or liquid.
Some other examples of colloids include are:
fog = water suspended in air
mud = dirt suspended in water
quicksand = sand suspended in water
milk = milk fat suspended in a water-based liquid
I explained that like thick mud if you get your foot stuck in it and move too quickly your shoe will come off and be stuck but the slower you move your shoe should come out but you will be very messy!
When I did this with Gabriel we also used a workbook we had picked up in the dollar bins at Target a while ago.
It is a way to add some other activities with the experiment. It had a place for him to write his prediction and basic instructions for making it. Then it had a basic explanation also. I added to it's information above though.
Beware where you do this or prepare by covering your surfaces. It get's kind of messy. The good part is it is also very easy to clean off of hard surfaces. Just use a rag with water and rub it off slowly.
Thank you to Brianna for helping me recreate this and for helping me word this post!
Next up we are going to make some Kool-aid taffy after we go pick up Gabee! See you then!
Grand Total = $1 for a box of cornstarch
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