Help your students comprehend the difficult concept of density with a lesson about objects that sink or float. The lesson introduces students to the concept of sinking and floating relative to an object’s density. Many students understand there are things that will float on top of the water and things that will sink. However, most students do not clearly understand why, especially when something heavy may float, like a cruise ship, but a small nail may sink. It is recommended students have ample opportunity to predict and then use hands-on experiments with objects that float or sink to fully understand the concept.
Sample Classroom Procedure / Teacher Instruction
- Say: A ship weighs thousands of pounds and a nail weighs just a few ounces. Ask: Why does the ship float and the nail sink?
- Allow for responses and discussion. Ask: What is different between the ship and the nail? What is the same?
- Allow for responses and discussion. Introduce sinking and floating.
- Distribute Sink or Float content pages. Read and review the information with the students. Save the final question for the lesson closing. Use the additional resources to enhance understanding.
- Distribute Activity page. Read and review the instructions. Pair students. Though working with a partner, each student will complete the chart, which is necessary since predictions may be different. Use about 15 different objects that can rotated among the students, set up at stations, or each pair of students receive each object. Rotate through the room reminding students to allow 30 seconds for the object to sink or float. One object may be a sponge. (Provide paper towels as well.)
- Once completed with the activity, students share their responses and answers to the questions following the chart. Discuss the differences between sinking and floating objects.
- Distribute Practice page. Check and review the students’ responses.
- Distribute the Homework page. Remind students to work with a parent when testing items for sinking and floating. The next day, allow students to share what sank or floated.
- In closing, ask: What do you think it would be like if you could float or walk on water? What would you do?
- Allow for responses and discussion.
Common Core State Standards:
CCSS.ELA-Literacy.RI.1.9, CCSS.ELA-Literacy.RI.2.3, CCSS.ELA-Literacy.RI.2.4, CCSS.ELA-Literacy.RI.2.9, CCSS.ELA-Literacy.RI.3.3, CCSS.ELA-Literacy.RI.3.4, CCSS.ELA-Literacy.RI.3.9
Class Sessions (45 minutes): At least 2 class sessions
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