Gak and Gravity

Slime was trending last year as it is still popular with school-age children. In our program, I often see the children playing with colorful, glittery slime they have made at home or purchased online.

Slime recipes differ. We make a substance with similar properties to slime called Gak. When I looked up the recipe for slime, some of the recipes were the same as the Gak recipe. The only difference is that Gak uses liquid starch as the catalyst instead of the contact solution many slime recipes use.

Whatever you call it, children enjoy working with this type of non-Newtonian material. We decided to create an invitation using Gak as the inspiration for our next exploration.

In our collection of recycled materials, we found some old-fashioned strawberry baskets. The square and versatile containers were perfect for our new invitation.

I selected three baskets and hung them about four feet above the floor, over a large table, with a fishing line. The baskets appeared to be floating above the surface and are where the investigation was about to begin.

We had some Gak already prepared from the previous day. I placed the Gak on the table so it would be ready for the children to discover. During our work session, many children noticed the Gak and started to play at the table. The children like stretching, rolling, making bubbles, and twisting the Gak as they play.

There is usually much discussion as the children play with new materials. The children share the properties of the material. They talk about how the material reacts with gravity and in their hands. Other tactile materials like Slime, Oobleck, clay, and dough invite similar reactions in the children.

As the exploration started, the children shared stories of past experiences playing with Gak. They shared ideas on how to make it. Many children expressed their love for the stickiness and messiness of the material. Experimentation was ongoing as the children created new ways to manipulate the material.

As the children worked, I waited to see if anyone would use the baskets hanging over the table. The children asked about them and then kept playing. I asked one child if I could use some Gak for an experiment. I grabbed a giant blob of Gak and placed it in one of the hanging baskets.

For a moment, we all stopped and watched the basket; nothing happened. Some of the children returned to playing with Gak. A few children continued to watch the blob in the basket. I asked the children what they thought might happen. The answer was universal, "I don't know." is a translation for I am having fun playing with Gak; who cares.

At that moment, I was thinking, why did you ask the children that question? I could have been more patient. I could have waited to see if the children had questions or made a discovery independently.

A few minutes later, tiny bubbles of Gak started to form on the bottom of the basket. The thickness of the Gak fought against the gravitational transformation process. Then it happened! A long string of liquefied Gak stretched from the bottom of the basket down onto the table.

The children stopped what they were doing to watch. Oohs and Aahs echoed around the small table where we worked. After witnessing the material's potential, children started to place Gak into the two remaining baskets. One basket filled with Gak and flowed well. The material was pouring out of the basket onto the table. The children were sticking their hands under the dropping Gak trying to catch it.

Much laughter and discussion ensued over how cool and absorbing the Gak had become as it flowed from the basket. The material did not change, but our experimentation with it did.

The invitation to combine the material with other objects in the classroom started a new investigative path.

Over the next few days, experimentations with Gak continued. The children worked together to find materials around the school that contained holes. Our investigation now centered on what could Gak flow through? Was there any material with holes that Gak could not penetrate, given the power of gravity?

We experimented with kitchen utensils, wire mesh, kitchen strainers, and smaller baskets. The Gak was successful in passing through all the objects. The time varied depending on the implementation we used.

The children explored time, pressure, viscosity, and gravity as the children played with Gak. They had fun experimenting and coming up with new ways to test the possibilities of the material.

The exploration of Gak provided a method for taking familiar material and finding new ways to explore its potential. This experience encouraged us to look at the materials we use and search for new ways to explore their limits. It gave us the inspiration to try new ideas and stretch our thinking.