Lesson Six

Lesson 6: What can we learn by examining the Moon’s surface?

 

Overview

In this lesson, students compare photos of the highlands and the mare on the Moon to determine the relative age of each, the crater density in each area, and to make an inference about what the early Solar System was like.

 

Standards Addressed

NGSS Crosscutting Concepts

  • Scale, Proportion, and Quantity

NGSS Science and Engineering Practices

  • Developing and Using Models

 

Materials

  • Student sheet (1 per student)
  • Full sized copies of Figure 2 and Figure 3 (1 per student, + extra)
  • Ruler (1 per student)

 

Lesson Sequence

Part 1

  1. Ask your students to imagine they are detectives in a murder case. The victim had been missing for some time and was just found out in the woods. You go to the victim’s house and see a stack of letters below the mail slot. As you look through the mail you find a very suspicious letter from a person that seems to be threatening the victim. This letter was buried under 50 other letters. Use your detective abilities to try to decide when the letter might have arrived. Have students state their reasoning and any assumptions that were made.
  2. Now we want to use these types of detective skills to look at the Moon. The Moon has a great number of craters on its surface. The craters come from large meteorites impacting the surface of the Moon. Figure 1 is an image of the entire Moon’s surface. The dark areas are called maria, which means seas in Latin. The brighter areas are called the highlands. Figure 2 is an image that shows a large portion of a mare. Figure 3 is an image that shows a portion of the highlands. Have students make a note of things they notice about Figure 2 and Figure 3. How are they different? How are they the same?
  3. The maria were thought to be big oceans by people hundreds of years ago. From the images, do you think that the maria are oceans of liquid water? What evidence can your students give to support their answer?
  4. Ask students to use their detective skills to try to figure out which features on the Moon came first and which came at a later time. Start with Figure 3 and see if they can identify four craters that can clearly be ordered in terms of oldest to youngest. Ask students to explain their reasoning for their order.
  5. Now look at Figure 2. Have students try to figure out which areas are older and younger. This includes the mare itself. Ask students to explain their reasoning.
  6. Finally, look at Figure 1. Ask students to try to answer the question: which is older the maria or the highlands? Explain your reasoning and test your reasoning by asking what would have to happen if my answer were wrong? Can you defend your answer with confidence?
  7. Ask students to summarize what their have learned about determining ages on the Moon. Can your students come up with a general principle which would always work to determine relative age between objects on the Moon?

Part 2

  1. Now let’s use our detective skills to gather more information. Students should go back to Figure 3 and measure, with a ruler, the width of the 10 largest craters they find in the image. Record this data and mark the craters that were used with a number that corresponds to the data. Hint: It may be helpful to outline the chosen craters with a marker or highlighter to make them easier to find later.
  2. Next, students should average all of their measurements and see what the average width is for the 10 craters. Then, compare their results with their partners. Are there differences? Discuss problems that they find in doing this exercise.
  3. Now move to Figure 2. Have students do the same measurements for 10 craters in the mare. Be sure to only use mare craters. How do their answers compare with their partners?
  4. Ask students to look at what they answered for the relative age of the highlands and maria from their Figure 1 Have them use this answer, and the average values they found for the highlands and the mare to make an assumption on the property of meteors based on their evidence.

Part 3

  1. Now we can gather even more data from these images. Ask students to draw a nice size box on Figure 3. Be sure to record the size of the box. Then, they should count all the craters they see inside the box. Record the data.
  2. Next, they need to draw the same size box inside the mare in Figure 2 and count the number of craters.
  3. Then, students should compare their results with their partners. Discuss any differences and why they occurred. Be sure to consider whether the differences are real or not. Determine the number density.
  4. Astronauts have visited both the maria of the Moon and the highlands. They have returned rock samples which have been radiometrically dated. The data showed that the maria formed on the moon about 3.5 billion years ago. The highlands formed about 4.5 billion years ago. This is also the age of the Earth and the rest of the Solar System.
    1. Using this information, have students look at the number of craters they counted from the highlands and the number from the mare and try to figure out how many of the craters in the highlands came about in the first 1 billion years after the Moon formed. Think carefully about what the data is telling you. Discuss your reasoning.
    2. From this investigation, you have the evidence to decide what the solar system was like in the first 1 billion years after it formed. Ask students to think about what they have learned from the data and use it to write a conclusion about what conditions were like in these early times.

Click Below for a Downloadable Version

Real lesson 6