Teaching Capacity and Mass in Kindergarten: Hands-On Measurement Ideas

There is so much for children to discover when they can pour, lift, predict, and test! When I first shared this post in 2014, I showed a few of the measurement activities we had tried in my Kindergarten classroom. I’ve updated it to focus on two attributes that are especially fun to investigate with concrete materials: capacity and mass.

If you’re looking for longer and shorter activities, I have a separate post about teaching length in Kindergarten.

What does the 2026 Ontario Kindergarten curriculum say about measurement?

In the 2026 curriculum, A10.1 asks children to describe different ways objects can be measured. A10.2 asks them to compare the length, area, mass, and capacity of objects using concrete materials. For capacity and mass, I want children to make predictions, test them with real objects, and explain what they notice. You can read the Kindergarten curriculum here.

The expectations no longer explicitly mention measuring with repeated non-standard units, but I still offer scoops, beans, counting bears, and cubes in some activities. They help children explore how we can measure. When I document their learning for A10, I focus on their ability to describe and compare what a container holds or how heavy objects are, rather than the accuracy of a particular count.

Compare capacity with containers

Capacity is how much a container can hold. I introduce it with two or three empty containers and ask, “Which do you think will hold the most? Why?” A tall, narrow cup beside a shorter, wider cup can lead to a great discussion because appearance alone doesn’t always settle the question.

Then we test the prediction. Fill one container with water and pour it into another. Does all of it fit? Is there room left over? Could we pour it back to check? Children get to see what holds more and holds less mean, and they can revise their ideas after trying it themselves. At a water or sand table, I leave out containers of different shapes and sizes so they can continue investigating during play.

I might ask:

• “Which container do you think holds more? What makes you think that?”
• “How could we check?”
• “What happened when you poured it into the other container?”

Another way to investigate: Use one small scoop or cup to fill each larger container. Children can count how many scoops they used and compare the results. In my unit, we also try this with beans and three cups. This is an engaging non-standard measurement experience; the most useful conversation for A10 is still about which cup holds more and how the children know. If comparing scoop counts, use the same scoop filled in the same way for each container.

Introduce mass with objects children can hold

For mass, I begin with the words heavy and light. We read Heavy or Light by Les Drew and brainstorm familiar objects that might be heavy or light. Then I give children two classroom objects to hold, one at a time, and ask which feels heavier.

In the original classroom activity, we used a water bottle as a reference point. Children suggested objects they thought would be heavier than or lighter than the bottle, and we added their ideas to a chart. Their suggestions make a good starting point for predictions; when possible, I let them handle the objects or test them with a scale to find out.

The words heavier and lighter become much more meaningful when children compare two specific objects. Something may feel heavy on its own but still be lighter than another object. I ask, “Which is heavier? How can we check?”

Test mass with a balance scale

A balance scale makes the comparison visible. Place one object in each pan and watch what happens. Children can predict which side will go down, then use the scale to check and explain the result. Try a pair that might surprise them: a larger, light object and a smaller, dense one.

The Which Is Heavier? centre in my printable unit gives children cards showing two groups of manipulatives. They build each group in the pans of a balance scale and see which is heavier. There is an optional recording page, but I especially want to hear children say what they predicted, what happened to the scale, and whether they changed their minds.

You can also leave a balance scale and a basket of familiar objects open during centres. For children interested in another way to measure mass, invite them to put one object in a pan and add identical manipulatives to the other until the pans balance. This is an exploration, not a requirement to reach a particular number of bears or cubes.

What should I observe and document?

I listen for children naming the attribute they are comparing, using words such as holds more, holds less, heavier, and lighter, and showing how they tested their ideas. A quick photo of their containers or scale setup, paired with a note about what they said, can capture their thinking.

If I haven’t yet observed a child comparing capacity or mass, I can sit with them and two objects for a brief investigation. “Which holds more?” or “Which is heavier?” gives them a chance to show and explain their thinking with concrete materials.

Area is also included in A10.2. I haven’t included a stand-alone area lesson or centre in my printable measurement unit, but children can explore it during play — for example, by covering two shapes with tiles and discussing which covers more space.

Ready-to-use measurement activities

Want the activities shown here? My printable Kindergarten measurement unit includes the capacity investigations, mass lessons, balance-scale cards, and hands-on centres, along with length activities. It retains non-standard measurement as an exploration. You can see the printable unit, digital activities, and the year-long Ontario Kindergarten Math System in the resource cards below.

I hope this helps make planning your measurement unit easy!

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