UNIT: MEASUREMENT

ACT-Based Science: Measuring Density and Material Identification
OBJECTIVE:

This activity helps students understand how to measure mass and volume accurately to calculate density. By comparing results to known values, students develop data analysis and critical thinking skills, reinforcing the importance of precision and accuracy in scientific measurements.

SCIENCE Thinking Challenge:

How does measurement precision impact density calculations?

Why is density an important property in material science and engineering?

How can density be used to identify unknown substances?

Applied Science Problem:

A student measures a metal cube with a digital caliper and finds its volume to be 8 cm³. Using a digital scale, the mass is determined to be 64 grams. What is the density of the cube?

2 g/cm³

4 g/cm³

8 g/cm³

10 g/cm³

MATEIRALS NEEDED:

Measurement tools: Digital calipers, rulers, scales

Objects of different materials (metal, plastic, wood)

Reference sheet with known densities

Worksheet templates for calculations

STUDENT DIRECTIONS:

Goal:

In this activity, you’ll measure the mass and volume of different objects and use your data to calculate density. Then, you’ll compare your results to a reference chart of known densities to help identify what material each object might be. This hands-on experiment helps you practice data analysis, scientific measurement, and ACT Science skills related to interpreting and applying scientific information.

Part 1: Prepare Your Tools and Materials

Gather the following materials at your station:

1 digital scale

1 digital caliper or ruler

3 different solid objects (e.g., metal cube, plastic block, wooden piece)

Density Reference Sheet (with known values for common materials)

Your Density Lab Worksheet

Part 2: Take Accurate Measurements

Measure the mass of each object using the digital scale:

Record the mass in grams (g) on your worksheet.

Be sure the scale is tared (zeroed) before each use.

Measure the dimensions of each object:

Use digital calipers or a ruler to measure length, width, and height (in cm).

Record your dimensions in the Volume Calculation section of the worksheet.

Calculate the volume:

Use the formula for volume of a rectangular object:

Write your volume in cubic centimeters (cm³) on the worksheet.

Part 3: Calculate Density and Identify Materials

Calculate the density of each object using this formula:

Record the calculated density (g/cm³) on your worksheet.

Part 4: Science Reflection & Analysis

Answer the reflection questions on your worksheet:

How does precision in your measurements affect the accuracy of your density calculation?

What might cause two students measuring the same object to get different densities?

Why is density useful in identifying unknown materials?

Class discussion (optional):

Share your findings with your group or class.

Discuss real-world examples where density is used (e.g., in material science, engineering, or manufacturing).