What is capacity?

Today for maths we did What is capacity.

This was challenging for me mostly but this was good to get better at my maths because it has subtraction answers and Addition answers as well But we had to write the answer not just say the answer . 

I learned about measuring how many UniLink cubes were in each container we had to fill , We had to fill the beaker , Red reading box , Plastic cup and a pencil holder.