1. Lesson 4.4 Estimating with Decimals
Everyday Math Grade 4
Lesson 4.4 Estimating with Decimals
Objective: To explain why decimals are useful; and to guide estimation of sums and differences of decimals.

2. Math message
Describe two ways in which decimals are used in real-life situations (write this in your ISN please!)

3. Why are decimals useful?
In your student reference book, find the page marked decimals and percents. (might be page 26)
Have you ever seen the trip meter on the speedometer in your car? (ask you parents to show it to you the next time you get in and have some time)
What is the purpose of this? (the number the is the whole number of miles travelled is usually in one color, and the number that is tenths of a mile travelled is usually in another color.)
What information would you get if the trip meter showed only whole numbers?

4.
Decimals make it possible to show more precise measurements. For example.. The vehicle above travelled 45 miles and 6 tenths of a mile. (not quite 47 miles)

5. With a partner With a partner, complete page 85 in your workbook.
-Read the first part of “A bicycle trip” and discuss with your partner what is meant by estimation. Then finish this page together.
Answer the page using ESTIMATION not exact answers.

6. Page 85 How did you answer problem 3?
There are many ways to complete it. One way is to estimate the sum of the distances travelled before and after lunch and then compare the totals.
Problem 7: You may want to count up from 25.8 to 26.0 (.2 miles) and then from 26.0 to 27.0 (1.0) more for a total of 1.2 miles.

7. Math Boxes
Math boxes for this lesson are on page 86 in your student workbook.

8. Homework
Homework for this lesson is page 113 – Railroad Tunnel Lengths
-Estimate the sums and differences of lengths of the worlds largest railroad tunnels.

9. Enrichment Page 116 is Enrichment – solving Gasoline mileage problems.
Estimate and use mental arithmetic strategies to solve mileage problems. Data on this page is approximate!

10. Further enrichment
If you would like further enrichment, check out page Solving a Decimal Magic Square Puzzle.
Can you use estimation to place decimals so that the sum of the numbers in each row, column, and diagonal of the magic square is equal to 6.5? Describe how you placed the decimal points.