This file includes four demonstrations and labs that you can easily set up and perform to help your students understand density and buoyancy. The activities include simple floating and sinking demonstrations, mass of cubes lab, density of liquid layers, and density of rectangular prisms. The materials that I used for the mass of cubes and density of rectangular prisms are available through Flinn Scientific. However, the lab themselves were designed by me to specifically help my students write a lab report. I have tested all of these lessons in my classroom and they have been effective. The labs are easy to set up and require relatively little prep time. I hope you will enjoy these labs because my students certainly did.