Second Grade · Math · week 10

Adding tens and ones (no regrouping)

Add 2-digit numbers by adding tens to tens and ones to ones, when no regrouping is needed.

To add two 2-digit numbers, add the ones together, then add the tens together. As long as the ones do not go over 9, you never need to regroup.

Line up the numbers by place: ones under ones, tens under tens. That keeps everything organized.

📋 For the teacher
Teach it (10–15 min):
  • Model lining up the digits by place value carefully -- a crooked line-up is the most common source of mistakes.
  • Add ones first, say the sum out loud, then add tens, then combine.
  • Use blocks or drawn tens-and-ones to show why you never need to trade this week -- the ones always fit under 10.
  • Once this feels solid, move quickly; regrouping comes next week and builds right on this.
Talk about it:
  • Why do we line numbers up by ones and tens before adding?
  • What tells you that you do NOT need to regroup in a problem?
  • Can you add 45 + 32 in your head by adding tens and ones separately?

Mastery looks like: They add two 2-digit numbers without regrouping accurately and explain adding tens and ones separately.

Common stumbles: Misaligning digits by place; adding all four digits together instead of ones-with-ones and tens-with-tens.

See it visually

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

Place ValueWatch ones, tens, hundreds, and thousands build big numbers.try →AdditionSee groups combine — with counters, blocks, and the number line.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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