As part of our Sink, Float, Density unit, the students used a dozen different materials to see if they would sink or float. Next, they made aluminum foil boats and tried to see how many marbles they could hold before they sank.
Each group of students was given a 6" x 6" sheet of aluminum foil. Some groupd got more than 50 marbles in their boat before it sank! We used this activity to talk about buoyancy and displacement.