Decomposition Lesson Plan

Instructor: Sharon Linde
Use this lesson plan to teach your students about the chemical reaction of decomposition. Students will read a text lesson defining the term and showing examples, then complete a lab to demonstrate understanding. Finish with a quiz to test understanding.

Learning Objectives

After this lesson, students will be able to:

  • define and explain decomposition reaction
  • successfully complete an experiment to show understanding of decomposition reaction


1 - 1.5 hours


  • Test tubes
  • Test tube holders
  • Hydrogen peroxide
  • Wooden splints
  • Safety glasses
  • Magnesium
  • Bunsen burners
  • Flint
  • Sodium hydrogen carbonate

Key Vocabulary

  • Chemical reaction
  • Decomposition reaction

Curriculum Standards

  • CCSS.ELA-Literacy.RST.9-10.3

Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks, attending to special cases or exceptions defined in the text.

  • CCSS.ELA-Literacy.RST.9-10.4

Determine the meaning of symbols, key terms, and other domain-specific words and phrases as they are used in a specific scientific or technical context relevant to grades 9-10 texts and topics.

  • CCSS.ELA-Literacy.RST.9-10.9

Compare and contrast findings presented in a text to those from other sources (including their own experiments), noting when the findings support or contradict previous explanations or accounts.

Warm Up and Preparation

  • Review concepts of chemical reaction with the lesson Common Chemical Reactions and Energy Change.
  • Take the quiz together to check understanding.
  • Zoom in on combination and decomposition reactions by writing the following on the board:
    • A + B = AB
    • AB = A + B
  • Ask students to talk to a partner to identify which is a combination reaction and which is a decomposition reaction, then discuss as a whole group, asking students to explain their thinking.
  • Allow students to ask any remaining questions.


  • Label the board 'Decomposition Reaction' and start the video lesson Decomposition Reaction: Definition & Examples.
  • Pause at 0:35 and work with students to write the definition on the board.
  • Ask:
    • What is necessary to have a decomposition reaction?
  • Play the remainder of the video lesson then ask lab groups to explain:
    • Why are car airbags an example of decomposition reaction?
  • Give the quiz as a checkpoint before moving on to the lab experiences.

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