Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.


Quarter 3
Quarter 4
Given a two-digit number, mentally find 10 more or 10 less than the number, with counting; explain the reasoning used.
Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
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Enduring Understanding

Understanding place value leads to number sense and efficient strategies for computation.

Essential Questions

How does a digit's position affect its value?

Vocabulary (online dictionary, HCPSS Vocabulary Cards)

add, subtract

About the Math

Mental computation with nice numbers such as ten, should be encouraged so that students see the relationships that exist between and among numbers. At first students may not see the relationship of adding ten and will need to count. The hundreds chart should be used to show how to add ten. This may mean that students need to place counters on the hundreds chart between 27 and 37 and see that is adding ten. After several examples, they may begin to see a pattern that moving down the hundreds chart one row is adding 10 and moving up one row is subtracting ten.

Rich Tasks for Multiple Means of Engagement, Expression, and Representation (UDL)

Use a hundreds chart so students have a visual representation of counting by tens, especially when you are counting off the decade.
Give the students a hundreds chart with missing numbers. The missing numbers should be ten more or ten less than other numbers. Ask students to fill in the missing numbers and explain why they chose the numbers they did.

Journal Prompt:

Turn over 2 digit cards to make a two-digit number. Find the number on your 100 chart. Record the number that is 10 more and the number that is 10 less. Repeat.
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Print Resources:
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Teaching Student-Centered Mathematics
(5.11,5.12)

Developing Number Concepts Place Value
Developing Number Concepts Place Value,
Multiplication and Division
(1-11, 1-12, 1-13, 1-14)

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Mastering the Basic Math Facts in
Addition and Subtraction
(pp. 63-75)






Web Resources:
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Games and Centers
Lessons
Student Resources
Video Segments
Online Games
100 Hunt Plus Ten
100 Hunt Minus Ten
Adding Ten Depthcharger

Printables
Ten More
What Number Is?
Adding Sets of Ten
Ladybug Lane
Full Lessons
Game of Tens and Ones
10 More 10 Less
How Many? +10/-10

Lesson Seeds
Skip Counting
Printable Tool
Hundreds Charts

Printable Activity Sheets
More or Less
Add on a Number Line
Hundred Board Magic
Sam's Base Ten Blocks
What Number Is?
Counting by Tens Video

Connecting Children's Literature:

Click on the books for additional activities.
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If You Give a Mouse a Cookie
By: Laura Numeroff

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Don't Eat the Teacher
By: Nick Ward


Questions/Comments:

Contact John SanGiovanni at jsangiovanni@hcpss.org.


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Howard County Public Schools Office of Elementary Mathematics Curricular Projects has licensed this product under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.