Home Experiment #3: Sink or Swim?
Have you ever tried to float in a swimming pool? You might have spread your arms out as much as possible and lay flat on your back.
Have you ever thought about why some objects float and which objects sink? What makes a pool noodle float? What makes your cell phone sink? (Please, trust me on that one. DO NOT test at home.)
Buoyancy is the ability to float. Buoyancy is a force. What kinds of objects have buoyancy? Why?
This activity is entirely customizable, from the ground up. You can choose which materials you have lying around the house and which container to use to make your test chamber. You can also make the testing more or less rigorous depending on the age and interest of the scientist. The discussion questions are what can make this experiment truly thought-provoking.
This video gives a brief overview of buoyancy and the experiment, in a way that can engage some of the younger scientists.
Home Experiment #3: Sink or Swim?
NGSS Standards:
K-PS2-1. Plan and conduct an investigation to compare the effects of different strengths or different directions of pushes and pulls on the motion of an object.
HS-PS2-1. Analyze data to support the claim that Newton’s second law of motion describes the mathematial relationship among the net force on a macroscopic object, its mass, and its acceleration.
Materials:
Open container of water
Various objects made of different materials
Procedure:
Predict which objects have buoyancy. Write down your hypotheses.
Test each object, one at a time, by gently putting it into the water. Record your observations.
Clean up!
Discussion Questions
Preschool and Elementary
Before: Which objects do you think will float? Why do you think this? What are these objects made of? What are the shapes of these objects?
During: Which objects have buoyancy? How do you know? What do these objects have in common? How are these objects different?
After: What do these objects have in common? How are these objects different? What other objects do you think might have buoyancy?
Middle School
Before: What else can you learn about buoyancy before making a hypothesis? What is your hypothesis? What are these objects made of? What are the shapes of these objects? What is density?
During: Which objects have buoyancy? How do you know? What do these objects have in common? How are these objects different? What forces are acting on these objects? What is the net force acting on these objects?
After: What do these objects have in common? How are these objects different? What other objects do you think might have buoyancy? What are some ways you can improve your experiment?
High School
Before: What else can you learn about buoyancy before making a hypothesis? What is your hypothesis? What are these objects made of? What are the shapes of these objects? What is density? Can you make a force diagram to describe the forces acting on an object floating in water?
During: Which objects have buoyancy? How do you know? What do these objects have in common? How are these objects different? What forces are acting on these objects? What is the net force acting on these objects?
After: What do these objects have in common? How are these objects different? What other objects do you think might have buoyancy? How might you calculate the density of these objects? How might density relate to buoyancy? How might you calculate the forces acting on these objects? What are some ways you can improve your experiment?
Resources for Enrichment