## 1.NBT.C.5

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

19 Lesson(s)

#### Students will engage in a variety of activities that ask them to represent numbers with groups of ten and have them counting by 10s.

#### Students will apply the idea of adding or subtracting ten to a number by adding or subtracting multiple groups of ten from a number.

#### The Number Grid Challenge. Students will play a game that requires them to add or subtract ten from a number using the number grid. They will record their results using standard notation.

#### Score this party a 10! Students will join in a 10 celebration as they choose from their favorite unit activities .

#### This lesson is More or Less a great lesson! Engage students in finding 10 more and 10 less than a number using these fun activities.

#### Are your students still counting to do 10 more? This lesson helps them explore how the numbers change when they repeatedly add 10 and why they change, helping push them towards mental math!

#### Students will use their ability to count by tens on and off the decade by taking part in an activity that requires them to start with a number of cubes and then repeatedly subtract ten.

#### Students will use the knowledge they gained during this unit to complete a variety of assessment tasks. Once they are finished, they will play a new activity.

#### Before First Graders are able to solve mentally, they must develop a concrete understanding of 10 less or 10 more than a given two-digit number. This lesson provides my students an opportunity to transition to solving mentally.

#### My class has been learning about place value and the meaning of tens and ones. This lesson will develop knowledge of adding or subtracting ten from a 2-digit number.

#### The CCSS emphasizes that students should be able to mentally add and subtract 10, without having to count. Help students develop a conceptual understanding of repeatedly adding 10s in this lesson-this promotes mental math!

#### Students will continue to explore the activities that were introduced in the previous day's lesson. The lesson will end with a discussion about subtraction equations where -10 is involved.

#### This task will offer a challenging activity and will also act as a piece of formative assessment as you look deeper into how well they can add or subtract ten from a number and plan your instruction from here.

Big Idea: