Lesson: Next Stop: Mars

Ask students to brainstorm measurements that would be very large or very small (e.g., the distance between Earth and the sun or the width of a strand of hair). Then ask: How would you write those measurements? How many zeroes would you need? How long would the numbers be? Then tell students they are going to learn about an easier way to write very large or very small numbers called scientific notation.

Play the video. Then ask the following questions:

• How has information about Mars been gathered? (A spacecraft flew by to take pictures in 1964. Since then, satellites, space probes, and rovers have explored Mars.)

• How are Earth and Mars similar and different? (They are neighbors in the solar system. Earth has water; Mars doesn’t have water, but it used to. Mars has a thin atmosphere; Earth has a thick atmosphere.)

• How are craters formed? (by objects hitting planets)

• What information do craters provide? (Craters help scientists investigate what is beneath the planet’s surface.)

• How do scientists collect information about what is under Mars’s surface? (A seismometer measures quakes, which helps determine the thickness of Mars’s layers.)

Have volunteers read paragraphs of the article aloud. Then ask the following questions:

• What exciting event is happening this month? (A new Mars rover called Perseverance is landing.)

• What hypothesis has NASA formed about Mars’s geology? Why? (Mars could have had flowing water and a thicker atmosphere because there are remains of dried-up rivers and deltas on Mars’s surface.)

• What does the rover have that can help us learn about Mars? (The rover carries cutting-edge technology, such as 23 cameras. It also has a navigation system and special wheels that allows it to go inside craters.)

Play the math video “Writing Scientific Notation.” Then read through the introduction and the example of the “Writing Scientific Notation” box on page 6 and ask:

• When do people use scientific notation? (when writing very large or very small numbers to save space and time)

• What is a very small number? (a number less than 1 that has many decimal places) Point out that the text in the example explains that a number less than 1 would require moving the decimal point to the right.

• How would n be different when writing a very small number in scientific notation? (The integer would be negative.)

Look for and address the following common misconceptions in students’ work when necessary:

• Using a factor (a) greater than or equal to 10: Remind students that the factor must be greater than or equal to 1 and less than 10.

• Placing the decimal point just before the first nonzero digit when working with decimal numbers: Remind students that the decimal point should directly follow the first nonzero digit.

• Negative exponents result in negative numbers: Remind students that negative powers of 10 are actually powers of 10 in the denominator, not negative numbers.

Have students research the population of their town, county, state, and country. Have them make a table listing each number in standard form and in scientific notation, rounding numbers to the nearest tenth when necessary.