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Rounding two- and three-digit numbers to the nearest ten on the vertical number line

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Rounding two- and three-digit numbers to the nearest ten on the vertical number line

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Shahed Taha

EDUC 268D- PTR Lesson 3

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1) Objectives

2) Introduction

3) Application problems

4) Concept Development

5) Student Debrief/Wrap-Up

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By the end of this lesson, students will be able to:

•Understand that rounding results in an approximate value.

•Round two-digit numbers to the nearest ten using a number line

•Round three-digit numbers to the nearest ten using a number line

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The gum Sheila wanted to buy costs 26 cents. Should she give the cashier 20 cents or 30 cents?

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Round

Rounding is a way to estimate or tell about how many

Rounding does not give an exact amount

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Round up

To increase a number to the nearest ten above it

Round down

To decrease a number to the nearest ten below it

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Less than

When one quantity is smaller than the other quantity

Greater than

When one quantity is more than the other quantity

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Benchmark Numbers

Endpoints based on which other quantities can be estimated

Midpoint

A point at the exact middle of a line segment

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What is 9 tens= __

On your personal whiteboards, write what are:

10 tens=

20 tens=

80 tens=

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130 and 140

830 and 840

560 and 570

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Problem 1: Round two-digit measurements to the nearest ten

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Problem 1: Round two-digit measurements to the nearest ten

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Let’s round 28 to the nearest ten

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When you look at your vertical number line, is 28 more than halfway or less than halfway between 20 and 30?

How did you know?

Plot it on the number line!

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Problem 2: Round three-digit measurements of milliliters to the nearest ten

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Problem 2: Round three-digit measurements of milliliters to the nearest ten

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Let’s round 17 milliliters to the nearest ten

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Problem 2: Round three-digit measurements of milliliters to the nearest ten

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Problem 2: Round three-digit measurements of milliliters to the nearest ten

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Let’s round 117 milliliters to the nearest ten

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When you look at your vertical number line, is 117 more than halfway or less than halfway between 110 and 120?

How did you know?

Plot it on the number line!

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Round the measurements to the nearest ten

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Round the measurements to the nearest ten

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75 mL

175 mL

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≈

Approximate symbol

=

Equal symbol

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Solve lesson 13 problem set exercises 1 and 2 only

Make sure you use the RDW approach when solving

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Solve the exit ticket lesson 13

Do you have any questions?