This activity is a hands-on lab that meets the Next Generation Science Standard for fifth grade - 5-PS1-1 Matter and Its Interaction: Develop a model to describe that matter is made of particles too small to be seen. Students learn that molecules and compounds are made of different combinations of elements. They have to determine which elements are in the given compounds and molecules, then build the compound/molecule with a molecular model set and, finally, sketch their constructions. My students truly loved this lab. They were able to understand how elements come together to form different compounds and how even one slight change in the number of elements in a compound can completely alter the compound formed. This lab would also work well with older students studying chemistry and molecular structures.