Lesson 8.2.1 Day 2 – Teacher Notes Standard: 8.EE.A.1 Know and apply the properties of integer exponents to generate equivalent numerical expressions. For example, 8.EE.A.3 Use numbers expressed in the form of a single digit times an integer power of 10 to estimate very large or very small quantities, and to express how many times as much one is than the other. For example, estimate the population of the United States as 3 times 108 and the population of the world as 7 times 109, and determine that the world population is more than 20 times larger. Full mastery can be expected by the end of the chapter. Lesson Focus: The focus of the lesson is to investigate how many times larger one number is than another, both given in scientific notation. (8-44 and 8-45) I can compare numbers written in scientific notation. Calculator: No Literacy/Teaching Strategy: Think-Pair-Share or Teammates Consult (Whole Lesson)

Bell Work

Earlier in this chapter you worked with expressions for interest problems.  You could rewrite them in simpler ways by using multiplication in place of repeated addition, and by using exponents in place of repeated multiplication.  Rewriting expressions in different forms can be a powerful tool for simplifying expressions and seeing patterns.  In this lesson, you will develop strategies for how to rewrite expressions using exponents. 

8-44. Scientific notation makes large numbers easier to write 8-44. Scientific notation makes large numbers easier to write. It also provides you with quick information about the sizes of the numbers. For example, Pluto and Haumea are both dwarf planets. Pluto has a mass of 1.305 × 1022 kilograms and Haumea has a mass of 4.006 × l021 kilograms. Without rewriting the mass of each planet, can you tell which of these dwarf planets is larger? Explain your reasoning.

8-45. Without using a calculator, estimate how many times bigger the larger dwarf planet is than the smaller one in problem 8-44.

Extra Practice If a satellite travels 62,000,000 miles from Earth, how can we write it in scientific notation? In Australia, the people use approximately 2,240,000,000 pounds of bread in a year. How can we write this number in scientific notation?

Extra Practice John is analyzing the mass of planets. The mass of Earth is 6.86246 x 10 25 . The mass of Jupiter is 2.8876 x 10 28 . Estimate how many times larger Jupiter is than Earth.

Extra Practice Write each number in scientific notation. 1) 5400000 2) .000006 3) .009 4) 71 x 10 3 5) .63 x 10 1 6) 2.66 x 10 4