Second Grade · Math · week 12

Adding within 100: blocks to numbers

Add 2-digit numbers within 100, with regrouping as needed, moving from blocks to the standard written method.

This week you connect the blocks to the numbers. Build both numbers with tens and ones, combine the piles, regroup if needed, then write the same steps with digits.

The blocks and the numbers should always match. If your blocks show a new ten forming, your written work should show a carried 1 too.

📋 For the teacher
Teach it (10–15 min):
  • Build both addends with blocks side by side before combining anything -- seeing two separate piles first makes the combining step clearer.
  • After combining and regrouping the blocks, have them write the matching equation right next to the blocks.
  • Gradually let them skip the blocks for easier problems once the written steps look automatic, but keep blocks ready for anything that trips them up.
  • Check the final answer by counting all the blocks in the combined, regrouped pile as one last check.
Talk about it:
  • How do the blocks show you when it is time to regroup?
  • Can you solve one problem with blocks and the same problem with just numbers, and check they match?
  • What is the hardest part of adding within 100 right now?

Mastery looks like: They add any two 2-digit numbers within 100 accurately using the written method, and can still show it with blocks if asked.

Common stumbles: Rushing to numbers before the block concept is solid; regrouping errors reappearing under time pressure.

See it visually

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

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.
← Back to todayAll coursesYear planner