First Grade · Math · week 11

Two-digit numbers are tens + ones

Decompose any two-digit number into tens and ones, such as 34 = 3 tens + 4 ones.

Every two-digit number is made of tens and ones. The first digit tells you how many tens; the second digit tells you how many ones. In 34, there are 3 tens and 4 ones.

Say it out loud: 34 is "3 tens and 4 ones," or 30 and 4 more. That is exactly what the digits mean.

📋 For the teacher
Teach it (10–15 min):
  • Use base-ten blocks (rods for tens, cubes for ones) so the two digits become physical piles.
  • Practice both directions: break a number into tens and ones, and build a number from tens and ones.
  • Point at each digit as you say its job: "this digit is tens, this digit is ones."
  • Use two-digit numbers from real life -- your child's age, a house number, a page number.
Talk about it:
  • What does the first digit of a two-digit number tell you?
  • What does the second digit tell you?
  • How many tens and ones are in your favorite two-digit number?

Mastery looks like: They break any two-digit number into tens and ones and rebuild a number from tens and ones.

Common stumbles: Mixing up which digit means tens and which means ones; reading 34 as "three and four" instead of three tens and four ones.

See it visually

Interactive, spoken-aloud tools that show this idea in motion.

Place ValueWatch ones, tens, hundreds, and thousands build big numbers.try →
Homework for this lessonType it, write it with a stylus, or print it for pencil & paper.open →
Records attendance + 15 min of Math for this learner.
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