Science: Sink, Float, and Buoyancy Experiments
Explore how objects act in water
Science: Sink, Float, and Buoyancy Experiments
Explore how objects act in water
Science - Grade 2-3
- 1
A student places a wooden craft stick in a tub of water. Predict whether it will sink or float. Explain your thinking.
Think about what happens to small pieces of wood in a pond or bathtub.
The wooden craft stick will probably float because wood is usually less dense than water and can stay on top of the surface. - 2
A metal paper clip is placed gently in a cup of water. It sinks to the bottom. What observation can the student write down?
The student can write that the metal paper clip sank to the bottom of the cup when it was placed in the water. - 3
Circle the object that is more likely to float: a rubber duck or a rock. Explain why.
Think about which object is often used as a bath toy.
The rubber duck is more likely to float because it is lighter for its size and may have air inside it. The rock is more likely to sink because it is dense. - 4
Mia tests three objects in water. The cork floats, the coin sinks, and the plastic bottle cap floats. Which objects floated?
The cork and the plastic bottle cap floated. The coin sank. - 5
What does buoyancy mean in a sink and float experiment?
Buoyancy is a force from the water that pushes up.
Buoyancy is the upward push of water on an object. This push helps some objects float. - 6
A ball of clay sinks in water. The same clay is shaped like a small boat and floats. Why can changing the shape help the clay float?
A wide boat shape spreads the clay out over the water.
Changing the clay into a boat shape helps it push more water out of the way and trap air. This can make the clay float even though the clay ball sank. - 7
A student says, "Heavy things always sink." Is this statement always true? Use an example to explain your answer.
The statement is not always true. A large ship is very heavy, but it can float because its shape helps it push water away and stay buoyant. - 8
Look at this test: a pencil floats, an eraser sinks, and a marble sinks. How many objects sank, and how many objects floated?
Two objects sank, the eraser and the marble. One object floated, the pencil. - 9
Before doing an experiment, why should scientists make a prediction?
A prediction is a careful guess based on what you already know.
Scientists make a prediction to say what they think will happen before they test it. Then they can compare their prediction with their observation. - 10
Design a simple sink and float test using a spoon, a leaf, and a toy block. What steps should you follow?
Good experiments test one object at a time and record observations.
First, fill a container with water. Next, predict whether each object will sink or float. Then place the spoon, leaf, and toy block in the water one at a time. Last, record what happens to each object.