Sink or Float

Our class has been studying matter and mass in science. Since it's autumn and pumpkins are a plenty right now we decided to asked the question "Do pumpkins sink or float?" We had various sizes small, medium and large. We started the lesson discussing two vocabulary cards. One saying sink, showing a picture of a sinking ship and another card saying float with a picture of a dog on a float in a pool. Before we placed each pumpkin in the water I had the children predict if they thought it would sink or float and then turn and talk with their partner and tell them why. We would then talk about why they thought their prediction would come true. One pumpkin after the other floated and the students became more and more excited as each pumpkin got larger. After discussing how pumpkins have a hollow air pocket inside to help them float I decided to cut a pumpkin in half a have them predict if it would float. After much discussion much of the class said no. With much anticipation we placed the pumpkin half on the water and the class erupted in a roar. They couldn't believe it floated! We discussed that water is very dense and that the pumpkin is less dense than water and therefore will float. The pumpkin has less mass than the water surrounding it. The children totally got the lesson and had a blast. Great job guys!