The Arizona STEM Acceleration Project

Plotting Your Own HR Diagram

Plotting Your Own HR Diagram

A 9th Grade STEM Lesson

Lynette Clark

January 2024

Notes for Teachers

• I did this lesson prior to getting too much into lesson on properties of stars.
• This lesson activity may also be done after students have learned about star properties as well.
• I think that after students were able to build this by just plotting according to their x and y axes, it allowed them to connect and understand star properties and vocabulary better throughout the unit.

List of Materials

• Large sticky pad posters (butcher paper works too)
• Envelope with Star Cards - printed in color
• Important to already have these cut out and all placed in an envelop prior to the lab activity (it will save a lot of time)
• Markers
• Scissors
• Yard or meter stick (for marking the x and y axes)
• Glue sticks
• HR Lab Activity Questions
• Axes Chart
• Blank HR Diagram

Standards

Earth and Space Science:

HS.E2U1.17 Construct an explanation of the origin, expansion, and scale of the universe based on astronomical evidence.

• The study of stars' light spectra and brightness is used to identify compositional elements.

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Mathematical Practices:

MP.4 Model with mathematics.

MP.6 Attend to precision.

Objective(s):

In this lesson, students will be able to:

• Construct a model of stars based on their luminosity and temperature. This will allow them to observe and determine the sequences of stars that coincide with the Hertzsprung-Russell (HR) Diagram.
• Understand how star properties are able to identify compositional elements.
• Know the difference between apparent and absolute magnitude.

Agenda (2 - 50 minute periods)

On the first day:

1. Review some general key terms: What is a star? Luminosity, temperature and units, mass, “cold and hot stars” and their colors.
2. Put students in groups of 3-4 and allow them to gather materials.
3. Introduce the x and y-axes for the plane of the plot.
4. Allow students to label their poster paper (large sticky pad or butcher paper) with their x-axis temperature. Give them the scale for this axis. Allow students to label their y-axis with luminosity and the scale.
5. Take out 3 random star cards from the envelope and talk through how students may place them on their labeled diagram. Allow students to practice placing the other 2 star cards they took out.

On the second day:

1. Allow students to gather their materials: labeled poster and envelope with star cards.
2. Make sure each group member at each poster has a pile of star cards and works to place them on their poster. This helps and allows all students to get the practice they need in using the terms and placing the stars depending on their properties.
3. Once all the stars have been placed according to temperature and luminosity, allow students to paste them on their poster.
4. Allow students to find trends (star groupings) on their poster according to where the stars are placed.
5. Hang posters and complete post-lab questions from their worksheet.
6. Explain how the stars on the posters are stars at stellar absolute magnitude. Compare stellar absolute magnitude to apparent magnitude.

Intro/Driving Question/Opening

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How does temperature and luminosity (star brightness) help us find things out about stars?

Hands-on Activity Instructions

• Suggested group structure - 3-4 students
• Day 1:
• Review some general key terms: What is a star? Luminosity, temperature and units, mass, “cold and hot stars” and their colors.
• Tell and allow students the x-axis represents temperature and y-axis represents luminosity. Give them the range of plots that need to be labeled on both of these axes.
• Take out 3 random star cards from the envelope and talk through how students may place them on their labeled diagram. Allow students to practice placing the other 2 star cards they took out.
• Day 2:
• Allow students to gather their materials: labeled poster and envelope with star cards.
• Make sure each individual group member at each poster has a pile of star cards and works to place them on their poster. This helps and allows all students to get the practice they need in using the terms and placing the stars depending on their properties.
• Once all the stars have been placed according to temperature and luminosity, allow students to paste them on their poster.
• Allow students to find star groupings on their poster according to where they placed their stars.
• Hang posters and complete post-lab questions.
• Explain how the stars on the posters are stars at stellar absolute magnitude. Compare stellar absolute magnitude to apparent magnitude.

Pictures

-HR Diagram I used to label (afterwards) is pictured

-Sample student HR Diagram is pictured →

https://i.pinimg.com/736x/44/5d/64/445d64b1222f644c4df3f47b193d87c2.jpg

Assessment

Post-lab worksheet - students will use the provided worksheet and their newly created HR diagram (they don’t know this is what this is called) to answer questions about stars.

Watch every student in every group place at least 5 star cards on their diagram.

Walk around class as students are doing the activity at all phases and ask questions about the star terms on their cards, their x and y-axes, and what trends they are noticing.

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Differentiation

• Have a blank HR Diagram already copied so student(s) may label their x and y-axes, color (according to the correct color stars are), label the star groups, and circle the sun.
• Provide key vocabulary and concepts with images.
• Provide additional support or assign a peer mentor if necessary.

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Remediation

Extension/Enrichment

• Continue to revisit the HR Diagram poster from this activity.
• After you have reviewed more content, allow students to title their posters Hertzsprung-Russell Diagram.
• Circle or highlight the star groups: Blue Giants, Red Giants, Main Sequence, and White Dwarfs
• Draw an arrow that points to where the sun is. Discuss this characteristic.

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