5.NBT.B.7

Decimal Force

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Game Info for Teachers

COMBINED RATING

4.0 Stars

TEACHERS (60)

4.3

STUDENTS (9673)

3.7

LENGTH

21 Minutes

GRADES

CAPABILITIES

Spanish Language Support

Text-to-Speech Support

Description

The evil Dr. Recode has taken control of the robotic members of Decimal Force! It's up to Decimal Prime and Dr. Maude to save the team with the power of decimal operations. Use decimal models to power up the Decimal Force satellite to find enemy agents, then solve decimal placement and addition, subtraction, multiplication and division problems to save your friends and stop Dr. Recode!

Vocabulary Words

decimal

decimal addition

model

grid

hundredth

tenth

one

multiply

divide

add

subtract

decimal placement

row

column

Instructions

Play through this interactive game to learn about Arithmetic with Decimals. Suitable for Grade 3, Grade 4, Grade 5.

Main Concepts

Use place value knowledge when multiplying decimals (A tenth by a tenth will yield a product of a hundredth).

The process of composing and decomposing a base-ten unit is the same for decimals as for whole numbers and the same methods of recording numerical work can be used with decimals as with whole numbers.

General methods used for computing products of whole numbers extend to products of decimals.

Add or subtract decimal numbers with models.

Add or subtract decimal numbers without models.

Multiply or divide decimal numbers with models.

Multiply or divide decimal numbers without models.

Base-ten units must be added and subtracted, so students need to attend to aligning the corresponding places correctly (this also aligns the decimal points).

Use the same place value understanding for adding and subtracting decimals used for adding and subtracting whole numbers.

Decimals are limited to thousandths and expectations for factors are limited to hundredths at this grade level, students will multiply tenths with tenths and tenths with hundredths, but they need not multiply hundredths with hundredths.

General methods used for computing quotients of whole numbers extend to decimals with the additional issue of placing the decimal point in the quotient.

A whole number is not usually written with a decimal point, but a decimal point followed by one or more 0s can be inserted on the right (e.g., 16 can also be written as 16.0 or 16.00). This reasoning can be used to put 0s in places so that all numbers show the same number of places to the right of the decimal point.

When multiplying by 0.1 and by 0.01 explain why the product is ten or a hundred times as small as the multiplicand (moves one or two places to the right). Extend reasoning to multipliers that are single-digit multiples of 0.1 and 0.01 (e.g., 0.2 and 0.02, etc.).

Discussion Questions

Before the Game

How are multiplication and division similar and different? How are addition and subtraction similar and different? What does it mean if a number has a decimal? How are the numbers to the right of the decimal different than the numbers to the left of the decimal? What do decimals represent in a number? Is adding, subtracting, multiplying and dividing with decimals all that much different than doing so with whole numbers?

After the Game

How is adding whole numbers vs. adding numbers with decimals the same and what is different? What is key to how to set up an addition or subtraction problem with decimals? How did you know where to place the decimal in the answer for multiplication and division? How did the grids help you understand how to find the answer to division problems?