Experiments with Playdough

One common playtime toy is playdough, which allows children to experiment with many mathematical concepts.

Conservation of Mass

One key mathematical concept that can be explored with playdough is conservation of mass. Mass is the word meaning the amount of dough; we usually interchange this with weight despite some small technical differences.

Conservation of mass is the idea that if you take the same ball of playdough and mould it into a different shape, the amount of dough does not change. Here, children can learn that the shape of the dough is not linked to the amount of dough. This explores the key concept that Shape and mass are different properties of an object.

Children could reshape the playdough and use scales to check that the weight of the dough has not changed. The volume of the playdough shapes must remain the same too, as we are not able to change the density of playdough. The mass, density and volume of an object are related by the equation: mass \(\div\) density \(=\) volume. As neither the mass nor the density of the playdough changes, the volume of the playdough object must remain the same too.

In the image below, we can see that the weight of the playdough recorded by the scales does not change as the shape of the playdough changes.

Three images of playdough on a set of scales. In each image, the playdough is in a different shape and the playdough weights the same.

Exploring Addition and Multiplication

Playdough can be a great tool for exploring addition and multiplication. By making balls of differing weights, the children can see how the total weight changes when they combine the different balls or weigh the different balls together.

In the image below, we can see that when we weigh the blue ball of playdough (\(10\)g) and the orange ball of playdough (\(20\)g) simultaneously, the total weight is \(30\)g. This demonstrates \(10+20=30\).

Three images of playdough on a set of scales. In the first image, there is a blue ball of playdough weighing 10g. In the second image, there is an orange ball of playdough weighing 20g. In the third image, the blue and orange balls are on the scale together weighing 30g.

Similarly, if the children made many balls of the same weight, they could see how the total weight increases as they add differing amounts of the balls to the scales. This allows them to simulate multiplication tables.

In the image below, we can see the same amount of playdough represented as \(1\) ball of \(100\)g, \(2\) balls of \(50\)g and \(4\) balls of \(25\)g. This illustrates how \(4\times25=2\times50=100\).

Three images of playdough on a set of scales. In the first image, there is a ball of playdough weighing 100g. In the second image, there are two balls of playdough, together weighing 100g. In the third image, there are four balls of playdough, together weighing 100g.

Spatial Reasoning

The children can also use playdough to explore spatial reasoning problems. They could section the same mass of playdough into different-sized balls and see how much of the initial amount of playdough they can fit into a container without distorting the balls. It will be easier to fit the total amount of playdough in the container if the balls are smaller, as there will be less wasted space in the container.

In the image below, we can see an example of this experiment. On the right-hand side, more of the playdough fits in the glass.

Two images of playdough in a glass. In the first image, there are two large balls of playdough which are stacked on top of each other in a glass and rise out of the top of the glass. In the second image, there are several smaller balls of playdough in the same glass; the smaller balls rise out of the glass less.

Ordering

The children can explore ordering sequences by using different-sized balls of playdough. They can come up with their own rules for how the sequence should be ordered, e.g. largest to smallest. In the image below, we can see a child creating different sized balls of playdough and placing them in order.

Different sized balls of playdough placed in order on a table.

Centre of Mass

By moulding a ball of playdough into different shapes and placing it at the top of a ramp, the children can investigate which shapes will roll and which won’t. This explores changing the centre of mass of the playdough and the area of the playdough in contact with the ramp. See our article on centre of mass to learn more about this.