Science Lesson Plans
Posted Apr 04, 2016 by Elmers
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    Dancing Molecules

    Engage students in a scientific inquiry activity that teaches the concept of molecular diffusion as they work through the scientific method. A great activity to use to introduce science fair!
    • 2 - 5
    • 1 hr
    • Science, Language Arts

    How do I get my class and myself ready? This lesson plan should give you everything you need to be prepared for the material.

    Lesson Plan Objective(s)

    Students will conduct a short scientific research project to investigate the concept of molecular diffusion. 

    Students will work through the scientific method to identify the proper steps to explore a problem and test their theories.

    Background Details

    Molecules diffuse rapidly through most liquids and gasses. Molecules in water collide with water molecules. Slight currents in the water from air movement or vibrations aid in the process of diffusion. Molecules move faster in hot water than in cold water. Adding food coloring to the water enables students to see this movement more easily.

    Materials Needed

    • food coloring
    • clear plastic cups
    • ice cubes
    • hot water
    • student handout (PDF download)

    Required Knowledge/Vocabulary

    molecule, compound, diffusion, collide


    CCSS.ELA-Literacy.CCRA.W.7 Conduct short as well as more sustained research projects based on focused questions, demonstrating understanding of the subject under investigation.

    How do I present the material? Here is the recommended approach, content and timing for presenting the materials.

    Lesson Instructions

    Introduce the lesson by showing the students a clear glass of tap water. Ask them if the water is moving or still. They will likely say that the water is still. Ask them to describe what is in the glass. Lead them through a discussion to discover that the water is made up of molecules. Explain that atoms and molecules of everything are constantly moving. 

    Introduce the scientific inquiry method by asking them how they might be able to see the movement of the molecules in the water. 

    Add a few drops of food coloring to the water and ask the students to describe what they see.

    Discussion Questions

    • What is in the glass?
    • What is in the water?
    • Do you see movement in the liquid?
    • What could we do to the water to see the molecules moving in the water?
    • Do you think the molecules would move faster in cold water or in hot water?
    • How can we test this?

    Activities (group or individual)

    Provide each student with a copy of the Molecule Diffusion PDF (handout download) and explain that they will make a hypothesis about whether molecules move faster in hot water or in cold water. Review the scientific method and the key vocabulary with them. 

    Provide small groups of students with the materials they need to conduct a short research project.

    Did my students achieve the lesson objective?

    Discussion Questions

    1. What other variables (besides temperature) could impact molecular diffusion? 
    2. What do you think might happen if we added sugar or salt to the water? Would the molecular diffusion speed up or slow down?

    Activities (group or individual)

    Extend the lesson by giving students the opportunity to explore molecular diffusion with liquids of different densities (i.e., salt water, sugar water, oil, etc.)

    Helpful Tips and Tricks

    This is a great activity to promote scientific inquiry and prepare students for science fair. Reinforce the scientific method and the components of the method.

    Student Feedback

    Students enjoy experimenting with different liquids to explore the movement of molecules.

    Lesson Plan Downloads


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