# Lesson: Rounding: Estimating Sum and Product

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### Lesson Objective

SWBAT round whole numbers in order to estimate to find a sum or product.

### Lesson Plan

Materials Needed: DN Worksheet, white board, dry erase markers, pencils, and IND Worksheet.
Vocabulary: rounding, estimation, actual, rounding off

……….
Do Now (2 - 3 min): On the board the teacher has the following 4 numbers written with different place values underlined. The teacher hands out the half worksheet and asks the students record the actual number, round to the underlined place value, and identify the place value of the underlined digit.

1. 56,901
2. 128,630
3. 782,901
4. 76,521

Opening (2 -3 min): Teacher quickly reviews answers to the Do Now and then says, “Today, we are going to put our knowledge of rounding to the test. We are going to begin estimation. I went over what estimation was on the first day of this unit. Estimation means to give a rough answer that may be a little less or a little more than the actual result. Yesterday we rounded to the hundred thousands place, so today we will begin estimating by rounding numbers to the thousands place and then estimating the answer. By the end of this lesson, you will be able to round whole number to the nearest thousands place in order to estimate a sum.”

Direct Instruction (10 min): Teacher begins “Ok! We are going to start today by looking at a word problem together. I am going to show you how estimation can help you find the correct answer and save you time on multiple choice tests.” The teacher has the following problem on the board or a chart and reads it aloud to students.

Example 1: 58 people are invited to the party; you are going to the store to buy supplies.  You figure that for each person you need two cups, two plates, and three napkins.  How many cups, plates, and napkins do you approximately need?

Example 2:

Actual   Estimation

6709                        7000
+  4100        ≈                   +   4000
___________ ____________
10,809                               11,000

Guided Practice (8-10 min): The teacher continues, “Ok, so let’s read and solve this question together using rounding and then estimation!” Teacher has the following two problems on the board or a chart.

Example 3: 92 people are invited to the party; you are going to the store to buy supplies.  You figure that for each person you need two cups, two plates, and three napkins.  How many cups, plates, and napkins do you approximately need?

Example 4: Ms. Tom has saved a lot of money for her son’s college. She has saved \$7,802 so far. Her sister has also been saving for her nephew’s college. She has saved \$2,341. Estimate to find out approximately how much money they have saved together.

Actual   Estimation

7802
+  2341     ≈     +
___________ ____________

Independent (10 - 18 min): The teacher hands out the IND worksheet. Students are asked to complete the worksheet independently and turn it in.

Closing (2-3 min): Teacher calls the attention of the students back toward the front of the class to quickly review the answers to the Independent Practice worksheet/ ask what we learned about.

### Lesson Resources

 IND Lesson 8   Classwork 1 DN Lesson 8   Starter / Do Now 1