Lesson Plan

Density Sink or Float Lab

Subject Area

Science

Grade(s)

5

Overview

This lesson will allow students to experiment with different objects to predict and explain the results of their experiments on the objects as they relate to density. Through this experiment, students will be able to understand the cause and effect relationship to explain the objects sinking or floating. 

This lesson results from a collaboration between the Alabama State Department of Education and ASTA.

Science (2015) Grade(s): 5

SC15.5.5

Construct explanations from observations to determine how the density of an object affects whether the object sinks or floats when placed in a liquid.

Unpacked Content

UP:SC15.5.5

Vocabulary

  • density
  • volume
  • buoyancy
  • data
  • observe
  • explain
  • sink
  • float
  • mass

Knowledge

Students know:
  • Objects are made of many tiny particles to small to be seen.
  • Some objects have many tiny particles compacted close together that causes the object to sink while other objects the same size may float because their tiny particles are less compact.
  • Some objects of the same size sink when others float.
  • Buoyancy is the ability of an object to float.

Skills

Students are able to:
  • Predict the results of different types of objects being placed in water. Test the objects and communicate the results.
  • Use appropriate tools (Scale, balance, ruler, or graduated cylinder) to measure the weight, mass, and/volume of an object.
  • Construct an explanation to describe the observed relationship between density and the ability of an object to sink or float.
  • Identify the evidence that supports the explanation that density affects the ability of an object to sink or float.

Understanding

Students understand that:
  • Cause and effect relationships are routinely identified and used to explain phenomenon like sinking and floating.

Scientific and Engineering Practices

Constructing Explanations and Designing Solutions

Crosscutting Concepts

Cause and Effect

Primary Learning Objectives

The students will be able to predict the results of different types of objects being placed in water. 

The students will be able to construct an explanation to describe the observed relationship between density and the ability of an object to sink or float. 

The student will be able to identify the evidence that supports the explanation that density affects the ability of an object to sink or float.

Procedures/Activities

  1. The teacher will begin the lesson by showing the short Density video to get students thinking about density. 
  2. Students will use the observation sheet to complete Part 1. Students will make observations of the physical properties of each object being measured. 
  3. Students will then complete Part 2. Students will predict if the object will sink or float in water. Students will also explain why they made the prediction they did.
  4. Students will complete Part 3. Students will put each object in the water and record if it sinks or floats. Students will also write any other observations they observed during testing. (Ex: The object sank slowly/quickly, or it sank at first but then floated back to the top.)
  5. Students will then complete Part 4. Students will construct their explanation to describe the relationship between density and the ability of an object to sink or float.
  6. At the end of the lesson, the teacher and the students will have a class discussion to wrap up their results of the lab. Use the lab sheet to guide the discussion.

Discussion questions may include:

    • Which objects did you predict would sink, were you correct?
    • Which objects did you predict would float, were you correct?
    • What are some differences between the objects that sank versus the objects that floated?
    • What in the object made it float/sink?
    • If something is denser than water, then it sinks. Why would the object be denser? (It has more matter in it.)
    • If something is less dense than water, then it floats. Why would the object be less dense? (It has less matter in it.)
    • Discuss a ping pong ball versus a golf ball because these two objects are about the same size. However, the solid golf ball has more matter in it so it sinks. The hollow ping pong ball has less matter in it and therefore floats.

Assessment Strategies

The teacher should observe students as they are working and question them to challenge their explanations. Students should receive a lab grade for completing and using valid explanations of the density of the objects. The teacher will use the student's completed observation sheet to check the following:

  • student's sink/float predictions.
  • accurateness of the student's explanation of the relationship between density and the ability of an object to sink or float. 

Acceleration

Students who finish early should access the following websites to get more practice with density: 

Virtual Density Lab - This virtual lab offers several different ways to experiment with density and will be a great resource for classrooms that have no density cubes. 

Intervention

Students who need help explaining the concept could pair with another student and work together through this process. Other students may need to transcribe for the partner. 

Approximate Duration

Total Duration

61 to 90 Minutes

Background and Preparation

Background/Preparation

Students should be familiar with 5.MII.3: gathering and analyzing objects to determine the different properties of each object.

Students also need to know the difference between sinking and floating. 

The teacher should have the Observation Sheet printed for students to fill out as they complete the experiment. This page can also be edited to add or take away the amount of objects being sampled. 

Review the rules of lab safety and clean-up procedures before they begin the experiment.  

Materials and Resources

Materials and Resources

Density cube set, one per group of students, or teacher may create a Density set using the following suggestions: 

  • toy soldier
  • die (dice)
  • small and/or large marble
  • eraser
  • egg
  • penny
  • nickel
  • dime
  • quarter
  • key
  • twig
  • ping pong ball
  • golf ball
  • bouncy ball

Clear tank to fill with water, one per group of students

Density Sink or Float Lab Observation sheet

Students may also use a scale, balance, graduated cylinders, magnets, or anything used in standard 5.MII.3 when gathering physical properties data. (Encourage students to get weight, mass, and volume of the objects for some of the properties.)

Technology Resources Needed

Student devices to access the following websites after the lab and observation sheet is complete: 

Density Video (2:18) - This video is used at the beginning of the lesson to engage students and get them thinking about density.

Virtual Density Lab - This virtual lab offers several different ways to experiment with density and will be a great resource for classrooms that have no density cubes. Note: The teacher must sign up for a free account at PhET. 

**If the class period has expired, have students access these sites. The teacher may consider using them for a whole group discussion the next day. The Virtual Density Lab describes objects of the same volume but with different densities. 

Approved Date

2016-05-10
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