A boat is able to float based on the amount of water it displaces or moves out of the way. When a boat pushes against the water, the water pushes back with an equal amount of force. Therefore, a wider boat is able to carry a heavier load than a long, narrow boat. Wider boats displace more water and therefore are held up by a greater water force, enabling them to carry heavier loads.
In this activity students will experiment with how much weight a boat can hold depending on the size of the boat.
Large pan with water
Toy boats (various sizes)
Pennies (or other coins)
- Place the boat in the water. Allow students to interact with the boat, seeing that it floats when placed in the water.
- Add pennies to the boat, counting how many are added before the boat sinks.
- Repeat this with each type of boat and compare how the boats differ in size, shape, and the amount of pennies they can hold.
Discussion Questions to Ask:
- What did the boats do when placed in the water?
- How many pennies do you think each boat can hold? Which boat held more pennies?
- If you had to make a boat to carry a heavy load, what shape and size boat would you make?
When teaching concepts related to density, it is best practice to allow students to experiment with different shapes and sizes of objects. Encourage students to explore how long objects can float before sinking, or how long it takes an object to sink when placed in the water. Finding ways to connect the activity to the students’ current interests is a great way to keep young students especially interested in the topic. Additionally, finding ways that this activity relates to the real-world is a great way to extend the science learning beyond the classroom. Looking at how large ships carry cargo, or how small ships can zip through the water very quickly, are easy ways to show how this lesson of buoyancy is applied in everyday life. For more fun buoyancy teaching tips, visit: http://bit.ly/ZrmMgg
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