This is a neat idea that works for kindergarteners to use nonstandard objects to help measure objects - in this case volume, a tough concept. Get a few small objects. They need to be different sizes - like a kid's size play tea cup, a regular cup, and maybe an empty peanut butter jar. Then for one of the objects, fill it with marbles without counting how many there are. Taking each marble out, count how many marbles /go into the container. Now task the child to figure out how many marbles go into the other objects. To make it fun, you could ask them to make an educated guess first - it will be eye-opening to see how many marbles really go into the object.