Adding and Subtracting Decimals with Models

Your students are probably very familiar with base-10 blocks. This particular math tool is usually introduced in first grade and is used every year when studying place value topics. Base-10 blocks can also be used to model decimals as well. When using these models, students do have to think about them differently. Let’s take a look at how each block can be used to represent a specific value.

• A flat, sometimes referred to as a hundreds block, represents 1 whole when working with decimals.
• A rod is used to stand for 1 tenth.
• A unit cube is used to represent 1 hundredth.

Let’s put this all together. If your student observes a collection of 2 flats, 5 rods, and 8 unit cubes, this represents the number 2.58. Students can use these models when adding and subtracting decimals through the hundredths place.

The goal of this worksheet is for students to add and subtract decimals using models. Students must look at 10 different addition and subtraction models, write down the equation, and solve for each. Students will also use the corresponding letters in each box to reveal the answer to a riddle at the bottom of the page.

An answer key is included with your download to make grading fast and easy!

Tips for Differentiation + Scaffolding 

For students who need a bit of a challenge, instead of adding visually, have students write the equations numerically for the problems and solve them using an abstract method. Students can also represent the answer to each problem with base-10 blocks.

If there are students who need additional support, encourage them to reference previous assignments, anchor charts, or a poster. Remind students what each base-10 block stands for when working with decimals.

🖨️ Easily Download & Print

Use the dropdown icon on the Download button to choose between the PDF or editable Google Slides version of this resource.

Because this resource includes an answer sheet, we recommend you print one copy of the entire file. Then, make photocopies of the blank worksheet for students to complete.

Turn this teaching resource into a sustainable activity by printing on cardstock and slipping it into a dry-erase sleeve. Students can record their answers with a whiteboard marker, then erase and reuse them.

Additionally, project the worksheet onto a screen and work through it as a class by having students record their answers in their notebooks.

This resource was created by Cassandra Friesen, a teacher in Colorado and Teach Starter Collaborator.

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