Library

Unit 7 - Lesson 15 - Grade 8: Illustrative Mathematics

By Formative Library
Last updated 2 months ago
13 Questions
Note from the author:
Grade 8 Unit 7
Lesson 15: Adding and Subtracting with Scientific Notation
CC BY 2021 Illustrative Mathematics®
Grade 8 Unit 7
Lesson 15: Adding and Subtracting with Scientific Notation
CC BY 2021 Illustrative Mathematics®
Lesson: Adding and Subtracting with Scientific Notation

Number Talk: Non-zero Digits (Warm Up)

Mentally decide how many non-zero digits each number will have.
1.

2.

3.

4.

Measuring the Planets

5.

Diego, Kiran, and Clare were wondering:

“If Neptune and Saturn were side by side, would they be wider than Jupiter?” They try to add the diameters, 4.7 x 104 km and 1.2 x 105 km. Here are the ways they approached the problem.
  • Diego says, “When we add the distances, we will get 4.7 + 1.2 = 5.9 . The exponent will be 9. So the two planets are 5.9 x 109 km side by side.”
  • Kiran wrote 4.7 x 104 as 47,000 and 1.2 x 105 as 120,000 and added them:
  • Clare says, “I think you can’t add unless they are the same power of 10.” She adds 4.7 x 104 km and 12 x 104 to get 16.7 x 104.

6.

Jupiter has a diameter of 1.43 x 105. Which is wider, Neptune and Saturn put side by side, or Jupiter?

A Celestial Dance

7.

When you add the distances of Mercury, Venus, Earth, and Mars from the Sun, would you reach as far as Jupiter?

8.

Add all the diameters of all the planets except the Sun. Which is wider, all of these objects side by side, or the Sun? Draw a picture that is close to scale.

Old McDonald's Massive Farm (Optional)

Use the table to answer questions about different life forms on the planet.

9.

On a farm there was a cow. And on the farm there were 2 sheep. There were also 3 chickens. What is the total mass of the 1 cow, the 2 sheep, the 3 chickens, and the 1 farmer on the farm?

10.

Make a conjecture about how many ants might be on the farm. If you added all these ants into the previous question, how would that affect your answer for the total mass of all the animals?

11.

What is the total mass of a human, a blue whale, and 6 ants all together?

12.

Which is greater, the number of bacteria, or the number of all the other animals in the table put together?

Cool Down: Adding with Scientific Notation

Adding with Scientific Notation

Elena wants to add (2.3 x 105) + (3.6 x 106) and writes (2.3 x 105) + (3.6 x 106) = 5.9 x 106.
13.

Explain to Elena what her mistake was and what the correct solution is.