Isolation of Phytochrome Mark as Favorite (1 Favorite)

LESSON PLAN in Interdisciplinary, History, Electromagnetic Spectrum, ACS National Historic Chemical Landmarks Program. Last updated August 31, 2022.


In this lesson, students will learn about plant cycles of development in relation to the electromagnetic spectrum through reading an article. There are a series of activities to help promote literacy in the science classroom related to the reading. This lesson could be easily used as plans for a substitute teacher, as most of the activities are self-guided.

Grade Level

High School

NGSS Alignment

This lesson will help prepare your students to meet the performance expectations in the following standards:

  • HS-PS3-2: Develop and use models to illustrate that energy at the macroscopic scale can be accounted for as a combination of energy associated with the motions of particles (objects) and energy associated with the relative position of particles (objects).
  • HS-PS4-3: Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other
  • Scientific and Engineering Practices:
    • Analyzing and Interpreting Data
    • Engaging in Argument from Evidence
    • Obtaining, Evaluating, and Communicating Information


By the end of this lesson, students should be able to:

  • Understand how light can interact with matter to alter properties.
  • Realize different parts of the electromagnetic spectrum can interact with matter differently.

Chemistry Topics

This lesson supports students’ understanding of:

  • The Electromagnetic Spectrum
  • Wavelength
  • Visible Light
  • Infrared Light
  • History


Teacher Preparation: 10 minutes
Lesson: Approximate times for students to complete each activity in the lesson:

  • Reading: 20 minutes
  • History Exercise: 20–25 minutes
  • Scientist Collaboration and Phytochrome: 10–15 minutes
  • The Electromagnetic Spectrum: 15–20 minutes
  • Phytochrome Predictions: 20–25 minutes


  • Reading document and any lessons that accompany it that you want to include.


  • No specific safety precautions need to be observed for this activity.

Teacher Notes


Lesson Overview:

The lesson includes multiple components as outlined individually below. The Reading is essential for all of the activities. Teachers can choose to do one or all of the included activities. Student handouts and corresponding answer keys are provided for each item described below:

  • Introduction: Introduce the lesson with a few conversation starters. Ask students to list different colors that they have observed in plants and the part of the plant in which each was seen. For example, students may mention pink flower petals, green leaves and stems, purple skins of fruit, etc. Ask what is present in plants to produce the colors. Have students share their thoughts as to what purpose these colored compounds (pigments) might have in a plant other than to provide color.
  • Reading: Isolation of Phytochrome
  • Activity: History Exercise: Chronology of Phytochrome Research
    • Students chronologically order phytochrome research events. They then place phytochrome research in the context of other scientific or agricultural developments.  
  • Activity: Scientist Collaboration and Phytochrome
    • Students recognize that many researchers may contribute to a particular discovery or body of knowledge and that a combination of different areas of scientific expertise of researchers can benefit a project.
  • Activity: The Electromagnetic Spectrum
    • In this activity, students will identify areas of the electromagnetic spectrum and specific wavelengths associated with the action of phytochrome. Then they’ll interpret what is meant by a photo-reversible reaction.
  • Activity: Phytochrome Predictions
    • Students examine properties that were predicted for phytochrome even before the pigment was discovered and isolated. They will relate each predicted property to the researcher's observations that support it.