The Why Behind Teaching This
Unit 6 teaches students about Earth's Place in the Universe. Standard 5-ESS1-1: Support an argument that differences in the apparent brightness of the sun compared to other stars is due to their relative distance from Earth, is one standard covered. Standard 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, is the other standard covered.
Throughout this unit, students will learn about classifying stars, patterns of stars, and the effects of rotation and revolution. We will be creating models, graphing data, tracing our shadows, and much more.
This specific lesson covers standard 5-ESS1-1 by building foundational skills and knowledge about classification of stars. In order to understand what affects the brightness of a star, it is important for students to understand how many stars are in the universe, and how scientists use properties to classify them. This lesson provides that foundational knowledge.
The goal of this lesson is for students to be able to use properties to classify stars and to identify the sun as a medium star that appears so bright because of its location.
Students will demonstrate success of this goal by accurately placing five stars, including the sun, on a graph identifying temperature, brightness, and size.
Preparing For The Lesson:
Groups will be sharing their posters so no other materials are needed
Introducing the Universe
I begin today's lesson by showing the Introducing the Universe PowerPoint. Although the focus of this lesson is on classifying stars, it is important that students have some background knowledge on how many stars there are out in the universe. The PowerPoint begins by defining the universe as all matter that exists in space. The next slide introduces galaxies and states that there are over 100 billion galaxies in the universe and that each galaxy is made up of millions of stars. This helps put into perspective how many stars are out there. The following slide identifies the galaxy that we live in as the Milky Way and pinpoints where the sun (our star) is located in the galaxy. Going over this slide serves two purposes, it allows me to identify the sun as a star, and it allows students to see that our star is just one tiny speck in the huge galaxy.
After going over the first three slides and discussing each one, I show the last slide. I provide each student with an index card to record their answers on. This serves as a pre-assessment so that I can see what they already know about star classification and the sun. It will also provide me with something to refer back to later in the lesson to make sure that any misconceptions have been cleared up. Students answer the 3 questions on their index card and then I collect them.
How Do We Classify Stars
I provide each student with a copy of the Star Classification Notebook Page that has already been cut to fit in their composition notebook. Students glue it into their notebook to take notes on while I teach how to classify stars. The note page is very brief, only providing a few details about the properties used to classify stars. Students will be researching specific stars and learning more about each property as they do so.
I place the classifying stars picture up on the overhead to refer to as I present the information orally. This picture is also found at the bottom of their research page that is used later in the lesson. By using this as a reference while I teach, I am able to model how to use the graph for the students. This will help make the graph a more useful tool for them as they research. When discussing the color in relation to the temperature I point out the temperature across the bottom of the graph so they can see blue is the hottest, then white/yellow/orange, and red is the coldest. When discussing size, I am able to point out that dwarf stars are at the bottom meaning they are the smallest and then giants in the middle and supergiants at the top.
The bottom part of the notes page refers to our star, the sun. It has blanks to fill in about the classification of the star using the properties discussed. We fill in that the sun is a yellow star and discuss what that means in regard to its temperature. We then fill in that it is classified as a dwarf star, meaning that it is one of the smaller stars (there are three categories of dwarf stars and the sun is in the largest of the dwarf classifications). Because it is medium in size we also discuss that it is also medium in brightness. We complete the last sentence by filling in: It only appears so big, hot, and bright to us because it is the closest star to us.
Researching Common Stars
Students are already sitting in table groups that consist of three students each. I provide each group with a lap top and a copy of the Classifying Stars Research page. The research paper has 5 common stars listed; The Sun, Polaris (the north star), Canis Majoris (largest star in the Milky Way), Proxima Centauri (closest star to the sun), and Sirius (the brightest star in the night sky). Groups research the stars and record the information in the chart.
After researching, groups create a poster that is a graph showing the temperature, brightness, and size similar to the one in the picture at the bottom of the page. They plot the five stars on the graph based on the information they found during their research. As you can see in the video of group creating star classification poster, I am rotating around to groups as they work on their posters to answer questions.
Sharing Our Findings
I hang all six posters up on the front board when groups are finished. We compare the location of each star on all the posters. We discover that only 2 out of the six groups completed their poster correctly. An example of one of the correct posters is below.
The other four groups did not place their stars in the correct place. All of the groups that illustrated incorrectly had a difficult time understanding and applying the concepts from the graph example. The graph used on their research page has the temperature at the bottom going from the hottest to the coldest. Students are not used to seeing a graph this way. They are used to seeing numbers at the bottom going to least to greatest. This threw many of them off when graphing their stars. An example of an incorrect poster is below.
The focus of our discussion is that the sun is located in the middle of each poster. Even though some groups graphed the stars backwards, the sun still fell in the middle so we were able to focus on this. The sun is a medium sized star, it is a yellow star which means it is not the hottest or the coldest, and it is medium in brightness too. I review what we put on the notebook page by asking If the sun is a medium sized star, with a medium temperature, and medium brightness, why does it look so big and feel so hot to us? Students respond that it is the closest to us.