S.T.E.A.M.

I have a group of high school students willing to help me start a S.T.E.A.M. club at the local elementary schools. S.T.E.A.M. stands for 'science, technology, engineering, arts, and mathematics'. It is the newer form of S.T.E.M. which left out the arts which really tie the whole thing together. I am looking for ideas that we can use to encourage interest in the sciences, mathematics, robotics, etc. We want to keep the kid interest level up while keeping the costs to a minimum. If you have any potential Instructables to add to my collection, please let me know.