All matter is made up of smaller and smaller bits. You can not see the small bits of matter. Atoms, they are too small to see. Most matter is made up of only one kind of atom, they are called elements. There is 109 different elements.
Water is made up of two elements.
Hydrogen and Oxygen Water is a compound that was formed when atoms of two or more different elements join together. Most of the matter on the earth are compounds. They will need some marshmallows and some tooth picks. Give the students ten tooth picks and a hand full of marshmallows. The students need to build a three dimensional complex compound.