Gak and Gravity


Slime was trending last year and is still popular with school age children. I often see the children playing with colorful glittery slime they have made at home or purchased online. 

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

Whatever you call it, this type of non-Newtonian material is beloved by children, so we decided to create a provocation using Gak as the inspiration for our next exploration.

In our collection of recycled materials, we found some old fashioned strawberry baskets. The green, square and versatile containers were perfect for our provocation into the properties of a non-Newtonian fluid.

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

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

There is usually much discussion as the children play with the material. The children share the properties of the material with each other and how the material reacts with gravity and in their hands. Similar tactile materials like Slime, Oobleck, clay, dough, and mudcreate similar reactions as the children play and explore the properties.

As the exploration started, the children shared stories of past experiences playing with Gak, and how they think it is made. Many children expressed their love of 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 large 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.” This is translation for I am having fun playing with Gak, who cares.

In that moment I am thinking why did you ask the children that question? I could have been more patient and waited to see if the children had questions or if they wanted to make the discovery on their own but this day I was not being patient.

A few minutes later small bubbles of Gak started to form on the bottom of the basket. The thickness of the Gak kept the gravitational process of transformation moving slowly. Then all of sudden 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 potential of the material, children started to place some of their Gak into the two remaining baskets. Now the first basket filled with Gak was flowing well, with material coming out of most of the holes and flowing onto the table. The children were sticking their hands under the dropping material trying to catch it.

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

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

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

Utensils, wire mesh, kitchen strainers, larger and smaller baskets were employed to experiment with. The Gak was successful in passing through all of the materials but the time varied greatly depending on the container utilized. 

Time, pressure, viscosity, and gravity were all being explored 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 the learning community with a method for taking a familiar material and finding new ways to explore it’s potential. This experience encouraged us, going forward, to look closer at the materials we use and to search for new ways to explore their limits. It gave us the inspiration to try new ideas and stretch what we think of as possible.