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 provides some background knowledge that will help students understand the components of standard 5-ESS1-2. This lesson teaches students about rotation and revolution which are directly linked to the length and direction of the shadow changing, day and night, and the seasonal appearance of stars. While teaching about the rotation and revolution of the Earth in space, comparisons will be made to the other planets. By comparing and contrasting all planets, students will have a better understanding of Earth's place in the solar system.
The goal of this lesson is for students to be able to compare and contrast the inner and outer planets.
Students will demonstrate mastery of this goal by creating a t-chart that correctly compares the inner and outer planets.
Preparing For The Lesson:
The Order of the Planets
I have a set of magnetic planets up on the front board. I tell my students the common acronym used to remember the correct order of the planets, My Very Excellent Mother Just Served Us Nachos. After saying it, I write the word that represents each planet under the magnetic picture of the planet. I point out that the only two planets that begin with the same letter, M, are Mercury and Mars. The word My stands for Mercury which should be easy to remember because Mercury begins with M and ends with Y which are the two letters in the word My.
I erase the acronym and have students repeat it to me several times. I mix the magnetic planets up and hand them to a student to go back up to the front board and put back in order. The student gets them correct and then mixes them up and hands them to another student to go up and put back in order. We repeat this with five students, all get them correct. I like to do this because it allows me to see that students know the order, but it also allows the rest of the class the chance to see them in order several times because they are responsible for checking the order and telling the student if he/she got it correct.
Grouping the Inner and Outer Planets
After the last student puts the magnetic planets in order, I draw a line between Mars and Jupiter. I tell students that this is where the asteroid belt is located. I define asteroids for them, asteroids are large pieces of rock, too small to be called planets, that revolve around the sun. I go on to explain that the asteroid belt separates the inner planets from the outer planets. The inner planets and outer planets have some similarities, but in most ways, are very different from each other. We create a Venn Diagram to compare and contrast the inner and outer planets.
We begin with ways they are similar, I ask students for ideas. They could tell from the pictures of the planets that they are all round. They also know from our discussion that they all revolve around the sun. I add that all planets rotate, or spin, on an axis. Students also remember that they are all located in the Milky Way Galaxy from a previous lesson in this unit. Then we move to the outer edges of the circles to add information about how they are different.
Because they are closer to the sun, the inner planets take less time to revolve and they have higher temperatures. Students can also tell from the pictures that the inner planets are smaller. The outer planets take longer to revolve and also have colder temperatures because they are farther from the sun. The outer planets are larger then the inner planets, and one student says that Saturn has rings. I tell the students that in fact, all the outer planets have rings, Saturn is the only one you can see with a telescope but they do all have rings. I add in a fact that students do not know, the inner planets have few moons and the outer planets have many moons. I do not tell them how many moons each has, they will discover this in the explore activity.
Another characteristic that is not mentioned is the composition of the planets. I review the word geosphere from the previous unit. Students tell me that the geosphere is the solid part of the Earth, the rock and minerals that make up the crust and mantel. I tell students that all inner planets are rocky planets similar to Earth. I ask if anyone knows what the outer planets are composed of. One student tells me gas. These planets are sometimes referred to as the gas giants because they are made up of gas and are larger planets.
While completing the venn diagram in the last section, our discussion remained very general. I want the students to be able to think critically about the information they know this far. They know the order of the planets, they know the inner planets are warmer and the outer are colder, they know the inner are small rocky planets and the outer are large gaseous planets, and they know it takes the inner less time to revolve around the sun. Now it is time for students to apply this new knowledge to some real numbers.
I provide each group (students are already sitting in table groups) with a large piece of bulletin board paper that has been divided into a large chart. The chart has the headings "Distance from the Sun, Size, Time to Revolve, Number of Moons, Temperature, and Surface". I provide each group with an envelope containing a set of the Planet Fact Cards that have been cut apart and mixed up. Each group finds a spot around the room where they can spread out the large chart and fill in the spaces with the facts about each planet.
The first thing that groups put on the chart are the names of the planets in order down the side. They then begin applying the information they learned while filling in the Venn Diagram to place the facts. Most groups begin with distance from the sun, time to revolve, and temperature. The only column they struggle with is the number of moons. When I tell them that the number of moons is related to the size of the planet because of the gravitational pull, groups begin getting those placed more easily.
Why Have Students Do This Activity
The facts about each planet are not the important content to get from this lesson. The similarities and differences between the inner and outer planets is the key concept. If students are able to think critically about how location affects the other characteristics, they will be able to remember the key differences between the two groups of planets. By doing this activity without me teaching specific facts, groups make a few common errors which allows me to focus attention on these areas. For example, all groups put the highest temperature for Mercury because it is the closest to the sun. I explain that Venus is actually the hottest planet because it has a very thick atmosphere that traps in all of the heat. Another common area is size. Many times students put the inner planets going smallest to largest and the outer planets going largest to smallest. While this is true for the outer planets, it is not for the inner planets. Mars is actually the second smallest planet and Venus and Earth are very similar in size. I take this opportunity to tell students that Venus and Earth are often called sister planets because they are very similar in size.
I provide each student with a copy of the inner planets versus outer planets comparison cards that have been precut and placed into baggies. I also give them a copy of inner planets versus outer planets t-chart. Students divide them into the correct categories and glue them under the correct heading. This activity allows me assess their understanding in a more fun way. The templates provided could also be used with Velcro to create a take away or station activity that students can use to practice with over and over.
The majority of students did very well on the assessment. Most of them that got 100% organized their sheet so that the matching facts were next to each other.
Those students who made even one error, did not demonstrate proficiency. The majority of these students did not organize their work and thus made errors. The most common error made was with the density. I reviewed this by holding up a rock and a balloon and asking which one was more dense. All students could tell me the rock. The inner planets are rocky and the outer planets are gaseous (this is a fact almost all students got correct) so the inner planets must be more dense. I think seeing this visual may help them remember this fact.