STEM related project to introduce students to what a liter is. Works well for providing hands on experience with what a liter is. Can be science or math and can be done in whole group, small group, partner settings, provided you have enough containers for kiddos to sort and the classroom management to handle kids working with water.
You will need:
5 containers that have more than/less than/just enough space for 1 L of liquid. (If you have multiple groups you will need multiple groups of containers.