Science Lesson: Comparing Floating and Sinking
In this lesson, students investigate how objects float or sink depending on their density and then investigate how changing the shape of an object can affect whether it floats or sinks.
Science Big Ideas
- Materials have different properties and certain properties can make a material useful for a particular function.
- Density is important for determining whether an object will float or sink.
- The shape of an object matters in determining whether it floats or sinks.
Discover Complete Hands-on Screens-off Core Science Curriculum for K-8 Classrooms
Prepared hands-on materials, full year grade-specific curriculum, and personalized live professional development designed to support mastery of current state science standards.
Science Essential Questions
- What properties of matter determine whether an object floats or sinks?
- Why is density a property of matter?
- Why would a bowling ball sink in fresh water but a beach ball float in the same water?
- How does changing the shape of an object affect whether it floats or sinks in water?
Common Science Misconceptions
Misconception: All big objects sink, while little objects float.
Fact: The most important factor in whether an object floats or sinks is its density. An object’s density is determined by the materials that make it up and its volume.
Misconception: The shape of a boat is unrelated to how well it can stay afloat.
Fact: A boat’s shape plays a major role in how buoyant the boat will be. Other factors that influence buoyancy include size and the materials of the boat.
Science Vocabulary
Density : a property of matter; the amount of matter packed in a certain amount of space
Float : to stay above the surface of water or another fluid such as air
Sink : to drop down in water or another fluid such as air
Lexile(R) Certified Non-Fiction Science Reading (Excerpt)
Floating in the Dead Sea
The Dead Sea is a body of water. People come from all over the world to visit it. It is famous because it is very salty. It is much saltier than the ocean.
People float easily in the Dead Sea. To float means to stay above the surface of water or another fluid such as air.
Density and Floating
Objects float when they are less dense than the fluid they are in. Density is a property of matter. It is the amount of matter packed in a certain amount of space.
The particles of a dense object are packed tightly together. The particles of a less dense object have more space around them.
Salt water is denser than fresh water. There are more particles in a cup of salt water than there are in a cup of fresh water. Both cups of water have the same amount of water. But fresh water doesn’t have many particles of salt.
Hands-on Science Activity
For the hands-on activity in this lesson, students investigate how objects float or sink depending on their density and then investigate how changing the shape of an object can affect whether it floats or sinks. In the first part of the investigation, students analyze the properties of different objects and then drop the objects into a water-filled test container to see if they float. In the second part of the investigation, students mold a clay ball into a shape that can float in the water. Students use the data they gathered from both parts of the investigation to construct an explanation about how the properties of an object affect whether it floats or sinks in water.
Science Assessments
KnowAtom incorporates formative and summative assessments designed to make students thinking visible for deeper student-centered learning.
- Vocabulary Check
- Lab Checkpoints
- Concept Check Assessment
- Concept Map Assessment
- And More...
See How KnowAtom Aligns to NGSS Science Standards
Discover hands-on screens-off core science curriculum for student centered K-8 classrooms. KnowAtom supports classrooms with all hands-on materials, curriculum, and professional development to support mastery of the standards.
