Density Lab

Simple Density Lab Lesson Plan

Learning Objective

Students will be able to calculate the density of various materials and understand how density relates to mass and volume. Comparing the different densities of materials. This helps them understand why some objects float in water while others sink, for example

Assessments

Students will, using the formula Density = Mass / Volume, answer conceptual questions related to the lab activity.

Key Points

• Density Definition: Density is defined as mass per unit volume.
• Formula: The formula for density is Density = Mass / Volume.
• Units: Common units for density include grams per cubic centimeter (g/cm³) and kilograms per cubic meter (kg/m³).
• Application: Understanding how density can help in identifying substances and understanding their properties.
• Misconception: Students may think that heavier objects always have a higher density, which is not true; density also depends on the volume of the object.

Opening

• Begin with a question: "What do you think happens when you mix oil and water?"
• Discuss students' predictions and guide them to think about the concept of density.
• Show a short video or demonstration of density in action (e.g., layering liquids of different densities).

Introduction to New Material

• Explain the concept of density and relate it to the lab activity.
• Introduce the formula for density, providing examples of mass and volume measurements.
• Anticipate the misconception regarding weight vs density and clarify this concept.

Guided Practice

• Set expectations for a collaborative lab environment.
• Provide students with different materials (e.g., marbles, water, salt water) and have them measure mass and volume.
• Guide students through calculating the density of each material, starting from simple objects to more complex ones.
• Monitor student performance by circulating the room, providing assistance, and checking calculations.

Measuring Volume

• For marbles: You can either use a displacement method:
  • Fill a graduated cylinder with water and record the volume.
  • Drop the marbles into the graduated cylinder, and record the new volume.
  • The difference between the initial and final volumes will give you the volume of the marbles.
• For water or salt water: Measure the volume directly using a graduated cylinder. The volume of water or salt water can be directly read from the cylinder in milliliters (mL). Since 1 mL is equivalent to 1 cm³, students can use this equivalence for calculating density.

Calculating Density

Once students have the mass and volume, they can use the density formula to calculate the density of each material.

Independent Practice

• Expect students to show their work and explain their reasoning for each calculation.
• Encourage them to reflect on how density affects the behavior of the materials.

Closing

• Conduct a brief discussion to summarize the key concepts learned about density.

Extension Activity

• Provide a challenge for students who finish early: Research and present on an application of density in real life, such as its role in designing ships or understanding buoyancy.

Assessment

Name ____________ Date ____________

Density is a material's mass per unit volume. The formula for density is ___________

Part 1: Pennies

Measure the mass of the pennies.

(Use the balance scale to measure the mass in grams.)

Mass of pennies: __________ grams

Measure the volume of the pennies. (Use the displacement method: Fill the graduated cylinder with water, then drop the pennies in and record the new volume. Subtract the initial volume from the final volume.) Initial volume of water (mL): __________ mL Final volume after adding pennies (mL): __________ mL Volume of pennies: __________ mL Calculate the density of the pennies. (Use the formula: Density = Mass / Volume) Density of pennies: __________ g/mL

Part 2: Water

1. Measure the mass of the water. (Use a balance scale to measure the mass of a known volume of water, or use the mass of water from the graduated cylinder directly.) Mass of water: __________ grams
2. Measure the volume of the water. (Read the volume directly from the graduated cylinder.) Volume of water: __________ mL
3. Calculate the density of the water. (Use the formula: Density = Mass / Volume) Density of water: __________ g/mL

Part 3: Salt Water

1. Measure the mass of the salt water.

(Use the balance scale to measure the mass of the salt water in the beaker.)

Mass of salt water: __________ grams

2. Measure the volume of the salt water.

   (Read the volume directly from the graduated cylinder.)

   Volume of salt water: __________ mL

3. Calculate the density of the salt water.

   (Use the formula: Density = Mass / Volume)

   Density of salt water: __________ g/mL

__________ has the highest density.

__________ has the least density.

In terms of the molecules, how tightly packed is each substance?