Grade 5 · Mathematics · 25 minutes

Decimal operations

Label ones, tenths and hundredths columns. Align place values when adding decimals.

Mr. S Teaches · Starter mini-lesson · elem-5-decimal-operations

Learning objective

Explain and practice decimal operations 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

5.NBT.B.7

Explain decimal calculations through hundredths using models and place-value reasoning.

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

Label ones, tenths and hundredths columns.
Represent 2.35 and 1.4 as 2.35 and 1.40.
Add matching units, regrouping when needed.
Estimate 2 + 1 before checking the exact result.

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.

OPTION 1 · YOUTUBE

Math Antics - Decimal Arithmetic

By mathantics

Connect this video to the lesson on decimal operations. Pause to try an example together.

Open on YouTube: Math Antics - Decimal Arithmetic (opens a new tab) ↗

OPTION 2 · YOUTUBE

Math Antics - Decimal Place Value

By mathantics

Review decimal place value before practicing the decimal addition example.

Open on YouTube: Math Antics - Decimal Place Value (opens a new tab) ↗

After watching

Explain how place value helps you add decimals. Estimate to check whether the answer is reasonable.

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

2.35 + 1.40 = 3.75. A trailing zero preserves value and aligns hundredths.

Try the starter activity

Model 2.35 + 1.4 using a place-value chart.

Student practice

Find 4.68 + 2.5 and explain the place-value alignment.

Quick check for understanding

Find the sum.

Sample answer and teacher guidance

Sample answer: 3.75

Listen or look for: 7.18; 8 hundredths plus 0 hundredths stay hundredths, while 11 tenths regroup to 1 one and 1 tenth.

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