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.