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5th Grade · Math · 5.NBT.B.7

Decimals Multiplication Lesson Plan for 5th Grade

A ready-to-teach decimals multiplication lesson for 5th Grade, built around decimal multiplication, powers of ten, counting decimal places, whole numbers times decimals, decimal times decimal. Print the plan, print the practice pages, and you are set.

Approximately 45 minutes

Learning objective

  • Multiply decimal numbers by 10 or 100 by shifting the decimal right
  • Recognize that multiplying by 10 moves the decimal one place right
  • Apply the pattern to compute products without long multiplication

Materials

Lesson steps

  1. 1. Warm up together (5 min)

    Open with three quick mental problems on decimals multiplication, hands down, answers called out together. You are checking who has recall and who is reconstructing every time.

  2. 2. Model it (I do) (10 min)

    Solve two decimals multiplication problems on the board, narrating the step most students skip. Then solve one wrong and ask the class to find where it broke.

  3. 3. Practice together (we do) (10 min)

    Work three more problems as a class. Ask a different student to supply each step rather than the whole answer. If a step stalls, drop back to concrete objects or a drawing before moving on.

  4. 4. Independent practice (you do) (15 min)

    Hand out "Multiply decimals with money notation". Students work independently while you circulate. Note who is fluent, who is counting on fingers, and who has not started, because that grouping drives tomorrow's small group.

  5. 5. Close the loop (5 min)

    Pull the class back. Ask one student to explain a problem they got right and one to name something that is still confusing. End on the confusion, not the success, so students learn that naming a gap is normal.

Check for understanding

Collect the practice pages and sort them into three piles: fluent, developing, and not yet. Any student in the third pile needs decimals multiplication retaught in a small group before the class moves on.

Differentiation

Extra support. Students who stall: pull them into a small group and rebuild decimals multiplication with concrete materials or a simpler text before asking for the written work again. Do not send the page home as homework, it will just rehearse the misunderstanding.

Extension. Students who finish early: ask them to write their own decimals multiplication problem for a partner to solve, then check the partner's work. Creating a problem is harder than solving one and it surfaces whether they really understand decimals multiplication.

Skills covered in this lesson

Multiply decimals by 10 or 100 · Multiply decimals by 10, 100 or 1,000 · Multiply 3-digit decimals by 10, 100, or 1000 · Multiply by 10, 100 or 1,000 (missing factors) · Multiply 3-digit decimals (missing factors) · Whole number x 1-digit decimal · Whole number x 1-2 digit decimal · Whole number x 1-2 digit decimal (harder) · Whole numbers x decimals (missing factors) · Whole numbers x 2-digit decimals (missing factors) · Multiply a decimal by decimal · Multiply decimals (missing factors)

Practice pages for this lesson

6 items, 6 printable pages that match the independent-practice step.

Questions teachers ask about teaching decimals multiplication

What decimal multiplication concepts do fifth graders learn?
Fifth graders multiply decimals by whole numbers and by other decimals, extending the standard multiplication algorithm (CCSS 5.NBT.B.7). The key conceptual understanding is placing the decimal point correctly in the product: the total number of decimal places in the product equals the sum of decimal places in the two factors. For example, 2.4 times 1.3: multiply 24 times 13 equals 312, then count decimal places (one plus one equals two), giving 3.12. This rule is a shortcut derived from thinking of decimals as fractions: 2.4 times 1.3 equals 24/10 times 13/10 equals 312/100 equals 3.12. Fifth graders also learn to multiply decimals by powers of ten (10, 100, 1000) by moving the decimal point, a shortcut that builds place-value understanding. Multiplying by 10 moves the decimal one place to the right; multiplying by 1/10 moves it one place to the left. Worksheets that require students to estimate the product first (is 2.4 times 1.3 closer to 2 or 3?) guard against misplaced decimal points.
How do you multiply decimals without a calculator?
The standard algorithm for decimal multiplication follows three steps. Step 1: ignore the decimal points and multiply the numbers as if they were whole integers. Step 2: count the total number of digits after decimal points in both factors. Step 3: place the decimal point in the product so that the same number of digits appear after it. For 0.6 times 0.04: multiply 6 times 4 equals 24. Count decimal places: one plus two equals three. Insert decimal: 0.024. Estimation confirms this is in the right range (about 0.6 times 0 is 0, and 0.6 times 0.1 is 0.06, so 0.024 is reasonable). A common scaffolding technique is to have students write the equivalent fraction multiplication alongside the decimal multiplication: 6/10 times 4/100 equals 24/1000 equals 0.024. Worksheets should mix single-decimal-place and double-decimal-place factors so students must count decimal places each time rather than applying a memorized number of places. Column multiplication on graph paper prevents alignment errors in the integer portion.
What are common errors in fifth-grade decimal multiplication?
The most frequent decimal multiplication errors are: (1) placing the decimal point by aligning it vertically with the decimal points in the factors instead of counting total decimal places, (2) forgetting to include leading zeros in the product when the integer multiplication gives a one or two-digit result but the decimal-place count requires a three or four-digit number (6 times 4 equals 24, but 0.006 times 0.04 equals 0.00024, requiring four decimal places and a leading zero), and (3) misapplying the powers-of-ten shortcut in the wrong direction (multiplying by 100 should move the decimal two places right, not left). Estimation is the most practical safeguard: have students round each factor to the nearest whole number or tenth and compute the approximate product before using the standard algorithm. If the exact answer differs from the estimate by more than a factor of 10, the decimal point is in the wrong place. Worksheets that embed estimation as a required step in each problem (write your estimate here, then solve) build this self-checking habit.

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