Videos and solutions to help Grade 3 students learn how to round two- and three-digit numbers to the nearest ten on the vertical number line.

Common Core Standards: 3.NBT.1, 3.MD.1, 3.MD.2

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Lesson Plans and Worksheets for Grade 3

Lesson Plans and Worksheets for all Grades

More Lessons for Grade 3

Common Core For Grade 3

New York State Common Core Math Module 2, Grade 3, Lesson 13

Application Problem

The school ballet recital begins at 12:17 p.m. and ends at 12:45 p.m. How many minutes long is the ballet recital?

Note: This problem reviews finding intervals of minutes from Topic A and leads directly into rounding intervals of minutes to the nearest ten in this lesson. Encourage students to share and discuss simplifying strategies they may have used to solve.

Possible strategies:

Count by ones from 12:17 to 12:20, then by fives to 12:45.

Count by tens and ones, 12:27, 12:37, plus 8 minutes.

Subtract 17 minutes from 45 minutes.

Concept Development

Let’s round 28 minutes to the nearest 10 minutes.

How many tens are in 28? 2 tens

What is 1 more ten than 2 tens? 3 tens

What number is halfway between 20 and 30? 25

In unit form, what number is halfway between 2 tens and 3 tens? 2 tens 5 ones

Estimate to draw a tick mark halfway between 20 and30. Label it 25 = 2 tens 5 ones.

When you look at your vertical number line, is 28 more than halfway or less than halfway between 20 and 30? 28 is more than halfway between 2 tens and 3 tens.

What is 28 rounded to the nearest ten? 30.

In unit form, 2 tens 8 ones rounded to the nearest ten is 3 tens.

Let’s go back to our Application Problem. How would you round to answer the question,

“About how long was the ballet recital?”

The ballet recital took about 30 minutes. Rounded to the nearest ten, the ballet recital took 30 minutes.

1. Round to the nearest ten. Use the number line to model your thinking.

b. 48 ≈ ___

d. 173 ≈ ___

2. Round the weight of each item to the nearest 10 grams. Draw numbers lines to model your thinking. Loaf of bread: 673 grams.

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