Part 2-The Light in Our Night Sky...Stars

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SWBAT explain how the appearance and brightness of stars is due to their relative distance from the Earth.

Big Idea

Students will construct a Hertzsprung-Russel diagram to illustrate and explain how a stars distance contributes to the brightness that is seen on Earth.

Lesson Overview

5e Lesson Plan Model

Many of my science lessons are based upon and taught using the 5E lesson plan model: Engage, Explore, Explain, Elaborate, and Evaluate. This lesson plan model allows me to incorporate a variety of learning opportunities and strategies for students.  With multiple learning experiences, students can gain new ideas, demonstrate thinking, draw conclusions, develop critical thinking skills, and interact with peers through discussions and hands-on activities.  With each stage in this lesson model, I select strategies that will serve students best for the concepts and content being delivered to them.  These strategies were selected for this lesson to facilitate peer discussions, participation in a group activity, reflective learning practices, and accountability for learning.

Unit Focus  

The Out of This World-A Journey Through Our Solar System unit focuses on students recognizing that Earth is a part of the “solar system” that includes the sun, planets, moons, and stars and is the third planet from the sun. Through models, investigations, graphing, and computer simulations, students learn that Earth revolves around the sun in a year’s time, and rotates on its axis once approximately every 24 hours. They make connections between the rotation of the earth and day/night, and the apparent movement of the sun, moon, and stars across the sky, as well as changes that occur in the observable shape of the moon over a month. The unit wraps up as students learn about the brightness of stars, patterns they create in the sky, and why some stars and constellations can only be seen at certain times of the year.

Lesson Synopsis

Part 2- The Light In Our Night Sky...Stars lesson begins with a demonstration using flashlights with three different colored bulbs to illustrate how the temperature of a star determines its color. Then students read about stars and their colors and take part in an activity to classify them. They use this information to diagram the different colors of stars according to their brightness, temperatures, and color using the Hertzsprung-Russell diagram and a series of questions to summarize their understanding. At the end of the lesson, students fill out a 3-2-1 exit ticket related to a star's brightness and distance.

Next Generation Science Standards  

This lesson will address and support future lessons on the following NGSS Standard(s):

  • 5-ESS1-1: Support an argument that the apparent brightness of the sun and stars is due to their relative distances from Earth.


  • 5-ESS1-2: Represent data in graphical displays to reveal patterns of daily changes in length and direction of shadows, day and night, and the seasonal appearance of some stars in the night sky.

  • 5-PS2.1: Support an argument that the gravitational force exerted by Earth on objects is directed down.


Scientific & Engineering Practices

Students are engaged in the following scientific and engineering practices...

2.) Developing and Using Models: Students develop a Hertzsprung-Russell diagram to analyze and describe the brightness, distance, size, and temperature of stars.


Crosscutting Concepts

Part 2- The Light In Our Night Sky...Stars lesson will correlate to other interdisciplinary areas.  These Crosscutting Concepts include:

3.) Scale, Proportion, and Quantity: Students construct an explanation that the apparent brightness of stars is due to their relative distances from the Earth.


Disciplinary Core Ideas

Disciplinary Core Ideas within this lesson include:

ESS1.A:  The Universe and its Stars

ESS1.B:  Earth and the Solar System


Classroom Management Considerations

Importance of Modeling to Develop Student

Responsibility, Accountability, and Independence 

Depending upon the time of year, this lesson is taught, teachers should consider modeling how groups should work together; establish group norms for activities, class discussions, and partner talks.  In addition, it is important to model think aloud strategies.  This sets up students to be more expressive and develop thinking skills during an activity.  The first half of the year, I model what group work and/or talks “look like and sound like.”  I intervene the moment students are off task with reminders and redirection.  By the second and last half of the year, I am able to ask students, “Who can give of three reminders for group activities to be successful?” Who can tell us two reminders for partner talks?”  Students take responsibility for becoming successful learners.  Again before teaching this lesson, consider the time of year, it may be necessary to do a lot of front loading to get students to eventually become more independent and transition through the lessons in a timely manner.


20 minutes

Activating Prior Knowledge

I have students recall our flashlight activity from yesterday and have a volunteer share what we learned from it. Bigger stars are brighter and the closer a star is to Earth, the brighter it appears.  I add on, our sun appears to be larger and brighter than the other stars in the sky to us because it is closer to Earth.

Sparking Curiosity

Then I say, "lets start off today with three flashlights." I point out that each flashlight has a different colored bulb in it, a red, yellow, and blue.  I position the three flashlights so they shine on the whiteboard. These lights shining are examples of some colors of stars we see in the night sky. Then I ask, where else have you seen these colors emitted with extreme heat and light? I ask students to make an observation and to turn and talk with their group. 

Then I project a video of a fire and ask students:

  • What do you see when you look at the hottest part of the fire?
  • What color do you see closest to the wood? (blue)
  • What do you notice when the flames are further away from the wood? (yellow-red)

I explain that the colors changed as the temperature did, just like stars. The temperature determines the color: blue stars are hot and bright, red are the coolest and least bright, and yellow stars are in between.


15 minutes

Why Are Stars Different Colors?

I tell the students we are using our chromebooks to read further about why stars change colors. We read this article together. I pause along the way to clarify and check for understanding. I explain that every time we come across the word red, yellow, white, or blue, we will stop and discuss what what facts. 

After reading the article I have them watch this minute and a half video. It a visual summary of the article we just read and helps students make the connection between a star's color and temperature.  


I ask students to write a one sentence answer (on the back of their graphic organizer) to the question: What can we learn from a star's color?  I am looking for students to show their understanding that a star's color can indicate the age of the star and its temperature. They should recognize that a blue star is very hot and is young. Whereas a red star is the coolest of all the stars and is nearing the end of its life.  Yellow to white stars are between a red and blue star. They are cooler than blue stars, but warmer than red stars. These colors indicate they are about half way through their life span.


25 minutes

Graphing Stars By Temperature

I project this image of the Hertzsprung–Russell (HR) diagram and share that it was created by two astronomers, Ejnar Hertzsprung from Denmark and Henry Norris Russell from the United States. They both discovered that the brightness of a star depends on the surface temperature of the star and created this diagram to illustrate the brightness, temperature, and classes of stars.

Herzsprung-Russell Diagram


I tell students they are going to create a Hertzsprung–Russell diagram to display the different colors of stars that we read about, red,yellow, white, and blue. I hand out a packet that contains a blank HR diagram and questions related to it. I explain the two parts to the class. The first part involves setting up the diagram. I guide through setting it up with labels, colors, and star outlines.  As they set up their diagram, we talk about the relationships between temperature, luminosity, color, and size. Then I ask them to observe the graph more closely now that it is created. They write down any patterns they notice within the diagram. To help them grapple with their observations I tell them to think about the relationship between temperature, color, and brightness of stars. Using their observations, I lead them through a discussion about these characteristics. Our discussion focuses on the effect distance has on a star. I point out that the size and temperature of a star determines its color and its distance from the Earth affect luminosity we see in the night sky

After our discussion, I point out part 2 of the packet. Part 2 is a series of questions related to their HR diagram. It requires them to analyze the graph by identifying specific parts of it, types of stars, how the stars are arranged on it, etc. I remind them of our discussion about distance, luminosity, color, and size.  These questions are intended to help students grapple with why some stars appear brighter than others. They work on these questions independently for the remainder of class and finish for homework if needed.  I collect them and as an assessment to lesson. I use this rubric assess students understanding.