MAFS.1.NBT.3.4 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.
Cognitive Complexity Level: 1-Recall
[divider] [/divider] Students are able to…
- Model sums to 100 using concrete, pictures and numerals
- Use mental strategies to add a two-digit number and a one-digit number
- Use mental strategies to add a two-digit number and a multiple of ten
- Record addition strategies in both vertical and horizontal formats
[divider] [/divider] Students are able to…because teachers:
- Provide problems for students to model addition problems with concrete materials
- Make generalizations about adding a one-digit number and a two-digit number
- Provide experiences with open numbers
- Pose purposeful questions to connect addition strategies and place value
- Facilitate conversations relating to addition strategies
[divider] [/divider] Questions to ask students:
- Ask: Describe a strategy to solve the problem 32 + 40?
- Sample answer that indicates understanding: I can start at 32 and count by tens. I need to add 4 tens. 32, 42, 52, 62, 72.
- Ask: Describe a strategy to solve the problem 54 +14?
- Sample answer that indicates understanding: I can start at 54 and add one ten to make 64. Then I need to count on by 4 ones. 64, 65, 66, 67, 68
[divider] [/divider] Additional Resources:
Additional in depth content knowledge
Blog Post:
http://smathsmarts.com/progression/
[divider] [/divider] Sample Formative Assessment Tasks:
[divider] [/divider] Resources/Tasks to Support Your Child at Home:
- Math Task: Give your child a story scenario involving adding/subtracting two 2 digit numbers (without regrouping). Encourage them to model or draw a model of the scenario to show how they found the sum or difference.
- Math Game: Using a deck of cards, dice or spinner: have your child create two different two-digit numbers. Have them add to find the sum. Have them subtract to find the difference. This could be modified into a war game where the person with the greatest sum or difference wins each round.