Density of Solid Objects

John Ombasa
Learning for Leadership Charter School
3300 5th St. Minneapolis, MN 55418
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Summary

In this science inquiry, students investigate whether volume or density of objects determine the floating or sinking of solid objects in water. Using a rock and a regular shaped piece of wood teachers engage students in the discussion of density, mass and volume. It is important the piece of wood chosen is bigger than the rock and the rock is small enough to fit in to the measuring cylinder. Students are first asked to make observations of both the rock and a block of wood. Based on the observation, each student states an hypothesis on what happens when both the rock and wood are placed in water.

Learning Goals

- student becomes familiar with density, volume, displacement and mass
- student better understands what numerical value determines the sinking or floating of solid objects in water
- student gains experience using scientific method and creating hypothesis
- student explores the concept of data recording and analysis

Context for Use

This activity can be done in a lab or a regular classroom, and students should work in groups of four in order to share their learning experience. It will require 90 minutes to have the discussion, experiment, and draw conclusions based on the findings.
Students should be able to work out division and multiplication of decimals.
Vocabulary: density, mass, displacement, and volume

Description and Teaching Materials

Materials needed:
- beaker
- measuring cylinder
- scale balance
- regular shaped wooden block
- rock
- work sheet
- water
- ruler
- calculator

Students will be guided through the process of determining the density of a regular shaped wooden block, by measuring the length, width and height with a ruler. Subsequently they can work out the volume using the formula: Volume = Length x Width x Height. Using a scale balance, the student measures the mass of the wooden block. The student then calculates the density of the wooden block by dividing the mass of the block by the volume to obtain the density of the rock. The student can also find the volume of the rock by displacement of water in the measuring cylinder.

Teaching Notes and Tips

Be careful when putting the rock in to the measuring cylinder. Chances are if you drop it, some water might spill out or the cylinder might break.
Ensure that students record their data in data sheets.

Assessment

Ask students to share their data with the class and ask them to turn in their data sheets so that you can see if they understood what they were doing.

Standards

Grade 9-12 History and nature of science
B. Scientific Inquiry
The student will design and complete a scientific experiment using scientific methods by determining a testable question, making hypotheses, designing a scientific investigation with appropriate controls, analyzing data , making conclusions based on evidence, and comparing conclusions to the original hypothesis and prior knowledge.

References and Resources