5th Grade Math Lesson

Hogwarts Decimal Potions: Adding to the Hundredths with Base-Ten Block Models

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5th Gradethinking classroom pedagogyCCSS.MATH.CONTENT.5.NBT.B.745 min

Learning Objective

Students will add decimals to the hundredths place by connecting base-ten block models to symbolic notation, including cases requiring regrouping.

Lesson Overview

Students work in random groups at vertical surfaces to discover how base-ten block models represent decimal addition to the hundredths place, progressing from simple tenths-only sums to multi-step problems requiring regrouping across place values — all framed within a Harry Potter potions context.

Materials

Vertical whiteboards or chart paper posted around the room
Dry-erase markers (multiple colors per group)
Base-ten blocks (flats, rods, unit cubes) — one set per group
Random grouping cards (playing cards work perfectly)
Individual whiteboards for the Mild/Medium/Spicy practice
Printed or teacher-drawn base-ten block reference chart (flat = 1 whole, rod = 0.1, small cube = 0.01)

Scaffolded Task Progression

1Task 1

Professor Snape's cauldron holds

0.3

liters of boomslang skin oil. He adds

0.5

liters more. Draw the base-ten blocks for each amount (remember: flat = 1 whole, rod = 0.1, small cube = 0.01). Then find the total. Write your answer as a decimal.

2Task 2

Hermione measures

0.24

liters of powdered bicorn horn. Draw the base-ten blocks for

0.24

. How many rods? How many small cubes? Now write the value of each block type.

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