Examples, solutions, videos, and songs to help Grade 1 kids learn how to add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used.

Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.

Common Core: 1.NBT.4

### Learning Targets:

• I can use concrete models or drawings to show a strategy based on place value (collecting tens, collecting ones, and if necessary, composing ten ones to make a ten) and other strategies (such as applying the operations properties) to add the following: a two-digit number and a one-digit number, a two-digit number and a multiple of ten, and a two-digit number and a two-digit number.
• I can write down and explain the steps that I followed as I used the concrete models or drawings to show how I added.
• I know the addition and subtraction fact families.
• I know how to model addition and subtraction using base ten manipulatives (e.g., base ten blocks, Digi-Blocks, Unifix cubes) and explain the process.

1.NBT.4 - Add a Two-Digit Number and One-Digit Number
This video explains how to adds a 2-digit number with a 1-digit number. This video illustrates 1.NBT.4 from the Common Core State Standards for Mathematics.
Examples:
12 + 4 = ?, 13 + 4 = ?, 15 + 4 = ?, 4 + 15 = ?, 12 + 8 = ?, 2 + 18 = ?

1.NBT.4 - Adding a Multiple of 10 to a Two-Digit Number
This video explains how to add a two-digit number and a multiple of 10, using concrete models and strategies based on place value. It uses number discs to show students how to solve the following problems:
Examples:
42 + 40 = ?, 50 + 36 = ?

Adding 1 and 2 Digit Numbers
Examples:
72 + 4 = ?, 38 + 5 = ?, 26 + 10 = ?, 55 + 7 = ?, 48 + 10 = ?

Long Addition - 1 by 2 digit numbers without carrying
This video introduces the basic idea to all long addition problems
Examples:
22 + 3, 34 + 4, 53 + 6, 54 + 5, 92 + 6

Long Addition - 1 by 2 digit numbers with carrying
Examples:
28 + 5, 37 + 9, 45 + 8, 99 + 9

Adding a 2 digit number and 1 digit with carry
Examples:
86 + 7 = ?

This video demonstrates adding two digit numbers without regrouping, showing the addition with longs and cubes (base 10 blocks)
Examples:
24 + 12

This video demonstrates adding two digit numbers with regrouping, showing the addition with longs and cubes (base 10 blocks)

How to add two 2 digit numbers with a carry.

Adding Two Digit Numbers (with Carrying

For Teachers

Grades K-2 / Math / Reasoning
CCSS: Math.1.NBT.C.4 Math.Practice.MP2 Math.Practice.MP3
Lesson Objective
Use multiple strategies to solve addition problems

1.NBT.4
The Common Core State Standards (CCSS) videos are designed to support states, schools, and teachers in the implementation of the CCSS. Each video is an audiovisual resource that focuses on one or more specific standards and usually includes examples/illustrations geared to enhancing understanding. The intent of each content-focused video is to clarify the meaning of the individual standard rather than to be a guide on how to teach each standard although the examples can be adapted for instructional use.<

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