➕ 2nd Grade Math · Unit 3

Adding and Subtracting Within 100

13 short narrated lessons in 3 chapters, each with pictures, a quiz with a hint and a second try, and an explanation for every answer.

Standards: 2.NBT.B.5 2.NBT.B.9 2.NBT.B.6 2.NBT.B.8

2nd Grade Math · 9 units
  1. 1Addition and Subtraction Fluency
  2. 2Place Value to 1,000
  3. 3Adding and Subtracting Within 100
  4. 4Adding and Subtracting Within 1,000
  5. 5Measuring Length
  6. 6Time and Money
  7. 7Data and Graphs
  8. 8Getting Ready to Multiply
  9. 9Shapes and Fractions
Picture from the lesson “Adding Tens and Ones”
Adding Tens and Ones
Picture from the lesson “Regrouping Ones”
Regrouping Ones
Picture from the lesson “Adding on a Number Line”
Adding on a Number Line

What your child will learn

Adding within 100

  1. Adding Tens and OnesAdd two-digit numbers by adding the tens and adding the ones.
  2. Regrouping OnesAdd two-digit numbers by trading ten ones for one ten.
  3. Adding on a Number LineAdd two-digit numbers by making jumps on an open number line.
  4. Why It WorksExplain why an addition strategy works using place value.
  5. Adding Within 100 Review ReviewReview adding two-digit numbers with and without regrouping.

Subtracting within 100

  1. Subtracting Tens and OnesSubtract two-digit numbers by subtracting tens and ones.
  2. Breaking a TenSubtract two-digit numbers by trading one ten for ten ones.
  3. Counting Up to SubtractSubtract by counting up from the smaller number to the bigger number.
  4. Subtracting Within 100 Review ReviewReview subtracting two-digit numbers and explaining strategies.

Mental math and many addends

  1. 10 More and 10 LessFind 10 more or 10 less than a number from 100 to 900 in your head.
  2. 100 More and 100 LessFind 100 more or 100 less than a number from 100 to 900 in your head.
  3. Adding Up to Four NumbersAdd up to four two-digit numbers using place value.
  4. Mental Math and Many Addends Review ReviewReview mental math with tens and hundreds and adding several numbers.

Try a question from this unit

From the lesson “Adding Tens and Ones”

Four rods and one cube labeled 41, a plus sign, and two rods and three cubes labeled 23.

What is 41 + 23?

  • [object Object]
  • [object Object]
  • [object Object]
Show the answer

[object Object]. 4 tens and 2 tens make 6 tens. 1 one and 3 ones make 4 ones. That is 64.

Hint kids see after a wrong try: “Add the tens. Then add the ones.”

Key words

  • tens
  • ones
  • regroup
  • number line
  • strategy
  • subtract
  • count up
  • mental math
  • hundred
  • addends
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Narrated lessons, pictures and quizzes for every grade from K to 8. Works offline.

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