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.

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

Quarter 3Quarter 4with counting;explain the reasoning used.without having to count; explain the reasoning used.

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

How does a digit's position affect its value?Essential Questions

add, subtractVocabulary (online dictionary, HCPSS Vocabulary Cards)

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.About the Math## Rich Tasks for Multiple Means of Engagement, Expression, and Representation (UDL)

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.

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.Journal Prompt:Print Resources:Teaching Student-Centered Mathematics

(5.11,5.12)

Developing Number Concepts Place Value,

Multiplication and Division

(1-11, 1-12, 1-13, 1-14)

Mastering the Basic Math Facts in

Addition and Subtraction

(pp. 63-75)

Web Resources:Games and CentersLessonsStudent ResourcesVideo Segments100 Hunt Plus Ten

100 Hunt Minus Ten

Adding Ten Depthcharger

Printables

Ten More

What Number Is?

Adding Sets of Ten

Ladybug Lane

Game of Tens and Ones

10 More 10 Less

How Many? +10/-10

Lesson Seeds

Skip Counting

Hundreds Charts

Printable Activity Sheets

More or Less

Add on a Number Line

Hundred Board Magic

Sam's Base Ten Blocks

What Number Is?

## Connecting Children's Literature:

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

Don't Eat the TeacherBy: Nick Ward

## Questions/Comments:

Contact John SanGiovanni at jsangiovanni@hcpss.org.Use and Sharing of HCPSS Website and Resources: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.