Density and Buoyancy Lesson Plan

Standards Addressed:

National Science Education Standards: Content Standards: 5-8A, 5-8B

California Science Standards: 8. All objects experience a buoyant force when immersed in a fluid. 8.a - density is mass per unit volume. 8-c - the buoyant force on an object in a fluid is an upward force equal to the weight of the fluid it has displaced. 8.d - how to predict whether an object will float or sink 9b - evaluate the accuracy and reproducibility of data.

 

Objectives:

  1. Students will know that density is mass per unit volume
  2. Students will understand that liquids have different densities
  3. Students will be able to predict whether an object will float or sink.
  4. Students will be able to reshape an object so that it will float, instead of sink, to come to understand that the buoyant force of an object is an upward force.

Materials:

rubbing alcohol

baby oil

water

cooking oil

dishwashing liquid

corn syrup

food coloring

500 ml graduated cylinders

25 ml graduated cylinders

50 ml beakers

variety of common objects: pencil eraser, coin, paper clip, toothpick, pushpin, rubber band, etc.

electronic balance

clay (enough for each partnership to have approximately 30 grams each)

clear pan or aquarium

paper clips

Lab sheets

After having measured mass, liquid volume, volume of irregular shaped objects and cubed objects so that students are familiar with the process, this lesson could be completed.

Procedures:

Part 1: Density Exploration

  1. Students observe density columns in the room and record observations.
  2. Students working in groups attempt to duplicate the column on a smaller scale.
  3. Students record observations and discuss what occurred.

Part 2: Density Investigation

  1. Students predict and observe as a variety of objects are dropped in the density column - predict how far it will go down and record observations
  2. Students working in groups choose from a variety of materials to predict, observe and determine which will float and sink.
  3. Students record information and discuss.
  4. Students are able to then discuss which has the least density and which has the most density. They also see that solid objects also have different densities than liquids.

Part 3. Buoyancy Experiment.

  1. Students determine density of clay ball and predict whether it will sink or float.
  2. Students reshape clay ball into a shape that has more surface area and displaces more water so that it will float
  3. Students attempt to float reshaped clay in pan of water.
  4. Students attempt to see how much cargo (paper clips) the "boat" will carry.
  5. Students write up lab report of findings.