Mr. S Teaches
Sign inRequest Tutoring
Menu
Sign inRequest Tutoring

Grade 2 · Mathematics · 20 minutes

Add within 100

Represent 36 and 27 with tens and ones. Use tens and ones to add two-digit numbers.

Mr. S Teaches · Starter mini-lesson · elem-2-add-within-100

Learning objective

Explain and practice add within 100 using the activity and evidence, then show the reasoning behind an answer.

Gather your materials

  • Paper and pencil
  • Counters, blocks or paper pieces
  • A ruler, clock model or grid when named in the steps

Use the items named in the teaching steps; paper models or adult-prepared photographs can replace physical equipment.

Common Core skill focus

2.NBT.B.5

Add and subtract within one hundred using place value or operation relationships.

Read the official standard ↗

Code and grade verified 2026-11-03. This mini-lesson addresses a selected skill, not the entire standard.

Teach it step by step

  1. Represent 36 and 27 with tens and ones.
  2. Combine 6 ones and 7 ones to make 13 ones.
  3. Exchange 10 ones for one ten.
  4. Combine the 6 tens and 3 ones and explain the regrouping.

Watch, notice, discuss

Video choices for this lesson

2 choices

Preview a video, then choose what fits your learners. “Show to class” opens a larger view; use the player’s play and full-screen controls when you’re ready.

Teacher preview needed. Check the language, level and length before showing. YouTube may show ads or related videos.

After watching

Use tens and ones to explain 36 + 27. Where does regrouping happen?

An external player loads only after you choose Preview or Show to class. Playback connects to YouTube. Videos belong to their creators; availability and embedding can change.

Make the thinking visible

Example to work through together

36 + 27 = 30 + 20 + 6 + 7 = 50 + 13 = 63.

Try the starter activity

Model 36 + 27; combine ones and regroup ten ones.

Student practice

Use drawings or blocks to solve 48 + 25, then explain the exchange.

Quick check for understanding

What is 36 + 27?

Sample answer and teacher guidance

Sample answer: 63

Listen or look for: 73; 13 ones become 1 ten and 3 ones.

Invite the learner to explain, demonstrate, draw or dictate their reasoning. Revisit a teaching step when the explanation is unclear.

Make it work for your learner

A little more support

Use a tens-and-ones chart and physical blocks before recording equations.

An additional challenge

Solve the same sum by adding 2 to 48 first, then the remaining 23.