Lesson Plan

Molecules on the Move

Subject Area

Science

Grade(s)

8

Overview

Students will design and conduct an experiment to see how temperature can affect the particle motion of water. The students will test molecular motion in different temperatures of water by adding food coloring to the water and observing the motion of the water molecules. This investigation will allow the students to see the movement of food coloring in water and how an increase or decrease in temperature will affect that movement.

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

Science (2015) Grade(s): 8

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Design and conduct an experiment to determine changes in particle motion, temperature, and state of a pure substance when thermal energy is added to or removed from a system.

Unpacked Content

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Vocabulary

  • Particle motion
  • Temperature
  • State [of Matter]
  • Pure substance
  • Thermal Energy
  • Kinetic Energy
  • System

Knowledge

Students know:
  • Changes in particle motion of a pure substance occur when thermal energy is added to or removed from a system.
  • Changes in temperature of a pure substance occur when thermal energy is added to or removed from a system.
  • Changes in state of a pure substance occur when thermal energy is added to or removed from a system.

Skills

Students are able to:
  • Identify the phenomena under investigation, which includes changes in particle motion, temperature, and state of a pure substance when thermal energy is added to or removed from a system.
  • Identify the purpose of the investigation, which includes determining changes in particle motion, temperature, and state of a pure substance when thermal energy is added to or removed from a system.
  • Develop a plan for the investigation individually or collaboratively.
  • Describe factors used in the investigation including appropriate units (if necessary), independent and dependent variables, controls and number of trials for each experimental condition.
  • Perform the investigation as prescribed by the plan.
  • Use data from the investigation to provide an causal account of the relationship between the addition of removal of thermal energy from a substance and the change in the average kinetic energy of the particles in a substance.

Understanding

Students understand that:
  • Adding or removing thermal energy from a system causes changes in particle motion of a pure substance.
  • Adding or removing thermal energy from a system causes changes in temperature of a pure substance.
  • Adding or removing thermal energy from a system causes changes in state of a pure substance.

Scientific and Engineering Practices

Planning and Carrying out Investigations

Crosscutting Concepts

Systems and System Models

Primary Learning Objectives

Learning Target: Students can design and conduct an experiment to determine changes in particle motion, temperature, and state of a pure substance when thermal energy is added or removed from a system.

Procedures/Activities

1. (15 Minutes) Watch the video Part(icles) of Your World: Crash Course Kids to introduce the concept of particles, phase changes, and thermal energy.

Ask the students the following questions:

Is the speed of water molecules different in hot and cold water?

Can we design a test to find out? 

(One way of accessing prior knowledge at this point would be to ask students if they have ever watched or helped make iced tea. Ask what was done to the water before the tea bags were added.)

2. (20 Minutes) Explain the students will be using food coloring to test particle motion in water with different temperatures. Have the materials listed on the board so that the students will know what is available. Ask the students to help design an experiment to test the effects of temperature on particle motion. Guide the students by asking questions like: Should we use the same amount of water in each cup? Should we use the same size cups? Should we use the same amount of food coloring? Should we put the food coloring in at the same time? Allow the students to come up with a plan for testing the effects of temperature on particle motion. Have them write down their plan in science notebook before going to the next step.

3. (10 Minutes) Allow the students to get the materials needed for conducting the experiment in their groups (The teacher will need hot and cold water available for students. If boiling hot water is used, please stress safety).

4. (15 Minutes) Have students conduct the experiment as planned out in their groups.  Remind the students to record the temperature of the hot and cold water prior to adding food coloring. Once they have recorded the temperatures, instruct them to add the food coloring at the same time and observe what happens. Note when changes occur. Note the time when they think the food coloring has sufficiently mixed.

5. (10 Minutes) Have students explain how temperature affected the motion of the particles and the speed at which the food coloring mixed with the water. Look back at your prediction from step one and explain why you were correct or how you would change your prediction. Summarize what you learned during this lesson.


1. (15 Minutes) Watch the video Part(icles) of Your World: Crash Course Kids to introduce the concept of particles, phase changes, and thermal energy.

Ask the students the following questions:

Is the speed of water molecules different in hot and cold water?

Can we design a test to find out? 

(One way of accessing prior knowledge at this point would be to ask students if they have ever watched or helped make iced tea. Ask what was done to the water before the tea bags were added.)

2. (20 Minutes) Explain the students will be using food coloring to test particle motion in water with different temperatures. Have the materials listed on the board so that the students will know what is available. Ask the students to help design an experiment to test the effects of temperature on particle motion. Guide the students by asking questions like: Should we use the same amount of water in each cup? Should we use the same size cups? Should we use the same amount of food coloring? Should we put the food coloring in at the same time? Allow the students to come up with a plan for testing the effects of temperature on particle motion. Have them write down their plan in science notebook before going to the next step.

3. (10 Minutes) Allow the students to get the materials needed for conducting the experiment in their groups (The teacher will need hot and cold water available for students. If boiling hot water is used, please stress safety).

4. (15 Minutes) Have students conduct the experiment as planned out in their groups.  Remind the students to record the temperature of the hot and cold water prior to adding food coloring. Once they have recorded the temperatures, instruct them to add the food coloring at the same time and observe what happens. Note when changes occur. Note the time when they think the food coloring has sufficiently mixed.

5. (10 Minutes) Have students explain how temperature affected the motion of the particles and the speed at which the food coloring mixed with the water. Look back at your prediction from step one and explain why you were correct or how you would change your prediction. Summarize what you learned during this lesson.

Assessment Strategies

Teacher observation and questioning

Check student notebook for understanding and completion. Did the student explain that particles move faster in warmer water? Did the student make a connection between particle motion and thermal energy? Did the student have a detailed and organized experimental procedure that would allow them to test for one variable? 

 

Acceleration

Students could research how rock candy is made and relate the process to thermal energy and particle motion. Explain why an increase in thermal energy can lead to supersaturated solutions.

Intervention

Give more structure and guidance to students/ groups that struggle with designing an experiment for testing one variable. The teacher might have to give assistance on creating the steps of the experiment.

Approximate Duration

Total Duration

61 to 90 Minutes

Background and Preparation

Background/Preparation

Students should know how to design an experiment that allows them to test for one variable. Students will be given the parameters for designing the experiment, but they must be able to control all variables except for the temperature of the water. Students should use the same amount of water and same amount of food coloring. This experiment is designed to scaffold the steps of designing an experiment, but the teacher can give more or less scaffolding depending on the students. 

This lesson is designed to be an introduction to particle motion, temperature, and thermal energy, so prior teaching on the topic is not necessary, however, students should be familiar with the concepts of molecules, temperature, and thermal energy.

Teacher must gather materials and have hot water and cold water available.

Materials and Resources

Materials and Resources

Per group: 2 clear plastic cups

Various colors of food coloring

Hot and cold water (Review safety guidelines if water is hot enough to scald)

Safety goggles

Droppers

Thermometers

Timer/Stopwatches

Science Notebooks

Technology Resources Needed

Computer with internet access

Projector for displaying youtube videos for students

Approved Date

2016-04-26
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