LESSON PLAN

Operations with Decimals

Apothem Team

Grade 7 · Computational Fluency

LESSON AT A GLANCE

Warm-up

5 min

Explore

15 min

Formalize

10 min

Practice

12 min

Exit ticket

3 min

Warm-up

Quick review: Add 1.2 + 2.3 (line up decimals). Subtract 5.7 - 2.4.

Explore

Students use base 10 blocks to model decimal addition and subtraction. Then, they use area models or arrays to multiply decimals (2.5 × 3.7 as a rectangle problem). Finally, they divide decimals using long division.

Formalize

Write the procedures:

Addition/Subtraction: Line up decimals, operate, bring decimal down. Multiplication: Multiply without decimals, then place decimal based on total decimal places. Division: Convert divisor to whole number if needed, then divide.

Emphasize: Decimal operations follow the same logic as whole number operations; place value determines where the decimal goes.

Practice

Students complete decimal operations (all four operations) on worksheets. Exit ticket: one multi-step problem.

Exit ticket

Students complete decimal operations (all four operations) on worksheets. Exit ticket: one multi-step problem.

TIP Use base 10 blocks and decimal grids for concrete understanding. Connect to whole number operations.

WORKED EXAMPLES

Calculate 3.6 + 2.4.

3.6 + 2.4 = 6.0 = 6.

Calculate 2.5 × 3.2.

25 × 32 = 800. Two decimal places total, so 2.5 × 3.2 = 8.00 = 8.

MATERIALS

•Base 10 blocks

•Decimal grids

•Calculators

•Place value charts

WATCH FOR

!Forgetting to line up decimal points in addition/subtraction.

!Miscounting decimal places in multiplication.

!Not converting the divisor to a whole number in decimal division.