Big Idea: Air is something real and takes up space. • I was walking along the river this weekend with my scientist friend and we saw a hot air balloon just hovering over the river. I told my friend that I would really like to know how it is possible for different objects like hot air balloons, birds, kites, and helicopters to float above the ground. My friend said, “That’s a great question, your thinking like a scientist. You should try asking your students to see if they could help you solve your question.” She gave me some great materials and ideas for investigations that we can try together. • What is the problem we need to solve? • What do we need to investigate?