Chemical Reactions
  • Using both a wet lab and LEGO bricks students understand chemical reactions
    Using both a wet lab and LEGO bricks students understand how chemicals react

This lesson is appropriate for children ages 11 and up.

The Chemical Reactions lesson introduces students to molecules, atoms, chemical notation, and chemical compounds (or reinforces these concepts) through an engaging hands-on wet lab, and LEGO® brick models of atoms.

The Chemistry lesson can serve many purposes in the curriculum:

  • An exciting introduction to a chemistry unit
  • A review when beginning a unit which uses previous knowledge of chemistry
  • An enrichment lesson after the students have an initial understanding of molecules and chemical reactions
  • A culminating lesson after students have completed a chemistry unit.

Teachers can also use the Chemistry activity to supplement other subjects that students may have studied. Some additional topics include:

  • Conservation of matter: as the students complete the LEGO bricks portion of the activity, they will see that every atom of the reactants is used to create the final products
  • Exothermic vs. endothermic reactions, or conservation of energy: the reaction of these chemicals is a surprisingly exothermic one.

This lesson is also offered as a 3-hour academic field trip LEGO Chemistry at the Edgerton Center. 

Lesson Overview

LEGO bricksChemistry begins with students doing a wet lab in a bag. The lab is from the GEMS guide “Chemical Reactions” which uses some fairly common materials for some very uncommon reactions. Students work through combinations of all or some of the materials to determine which were responsible for particular reactions. We go over proper lab procedure for a chemistry experiment, although not lab writeup.

We next go over some vocabulary pertinent to chemistry, and chemical reactions. It is at this time that we explain that each LEGO brick represents one atom, and that different color LEGO bricks represent different elements.

We discuss molecules, mixtures and compounds. Students practice writing chemical formulas (although not equations). Finally, using the LEGO bricks, students will model the original chemical reaction from the wet lab, and can see how the atoms recombined to make new molecules.

Wet Lab

Please see the Teacher's Guide for a list of supplies needed for the Wet Lab. Many of these can be purchased at local stores. We obtained our phenol red from Sargent-Welch.

This 7.5 minute Video of the Wet Lab may be useful for teachers to view prior to doing the wet lab with their students. It can also be useful to lead students though the steps. It shows the results of the optional "Part E Further Experiments" (p. 2 on student worksheet. p. 11 in teacher's guide) if the teacher does not have time to do this with the class.

LEGO Bricks Lab

The LEGO bricks can be used for our Photosynthesis and Understanding Air lessons as well. The  Atoms and Molecules Layout Mat shows the LEGO bricks we recommend for all of the lessons. We chose these bricks because they can be used to illustrate a number of chemical and biological concepts. Their colors match those commonly used in other chemical models, though other colors may be substituted. The layout mat can also be used as an easy clean up tool to check if students have all of their bricks.

Building blocks (such as LEGO) can be purchased from toy manufacturers or the Web site. You might also arrange a LEGO brick donation with your local Parent Teacher Association. 

Supporting Documents

For educators wishing to teach this lesson in their own classroom or after-school program, we provide the following documents. The LEGO Sets were updated in June 2012 and the current documents are listed below and in the right side bar of this page. Earlier versions are listed separately at the bottom of the page.

Trouble downloading these files? Email

Interactive Video

An interactive video called "Recognizing Chemical Reactions," with Dr. Kathleen Vandiver (inventor of this lesson) and produced by BLOSSOMS can assist you in teaching this lesson. A video of the teacher's guide and a written transcript can be found here. BLOSSOMS (Blended Learning Open Source Science or Math Studies) is a collaborative initiative seeking to begin to develop a large, free repository of video modules for high school math and science classes created by gifted volunteer teachers from around the world, seeded initially by MIT faculty members and by partnering educators in Jordan and Pakistan.

Curriculum Standards

This lesson meets the following items of the Massachusetts State Frameworks for grades 6-8, Physical Sciences Strand: Elements, Compounds & Mixtures:

  • 5. Recognize that there are more than 100 elements that combine in a multitude of ways to produce compounds that make up all of the living and nonliving things that we encounter.
  • 6. Differentiate between an atom (the smallest unit of an element that maintains the characteristics of that element) and a molecule (the smallest unit of a compound that maintains the characteristics of that compound).
  • 7. Give basic examples of elements and compounds.
  • 8. Differentiate between mixtures and pure substances.
  • 10. Differentiate between physical changes and chemical changes.
Document Versions prior to June 2012

PDF icon 2009 Version - Reactants and Products
PDF icon 2009 Version - Atom and Molecules Layout Mat

Contact us if you would like to learn how to use the materials at our next workshop, or if you would like to inquire about a complete classroom set of materials including LEGO bricks.

LEGO®, the LEGO logo, and the brick and knob configurations are trademarks of the LEGO group, used here with permission. ©MIT. All rights reserved.