Find the Missing Side When Given the Perimeter

Once your students understand how to calculate the perimeter of shapes by adding the measurements of all sides together, they are ready to move on to more complex questions involving perimeter. Often, the next step is teaching your students how to determine the missing length on a shape when provided with the perimeter and remaining side lengths.

This missing side perimeter worksheet is the perfect resource to help your students practice calculating the missing sides of squares and rectangles. Students are provided with the total perimeter and one of the side lengths. The students must use this information to calculate the missing side length.

This worksheet requiring students to find the missing side when given the perimeter consists of 10 questions spanning two pages. An answer key is also included in the download to make grading quick and easy!

This perimeter worksheet comes in four different file options. These are:

• Color printable PDF
• Black-and-white printable PDF
• Color editable Google Slide
• Black-and-white editable Google Slide

More Practice Finding the Perimeter of the Missing Side

Are you looking for ways to support the needs of all students while using these missing side perimeter worksheets? Here are a few suggestions:

• Support with Concrete Materials – If you have students who require some additional support in order to complete this missing sides perimeter worksheet, then we suggest providing concrete materials such as rulers or string to help students physically measure out the perimeter of the shapes.
• Extend with Word Problems – Challenge students to write word problems for a selection of the shapes on the worksheet. Be sure the students relate their word problems to real-world scenarios.

Download This Missing Side Length Worksheet

Use the download button above to select your preferred file option. (Note: You will be prompted to make a copy of the Google Slides template on your personal drive before accessing it.)

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. 

More Perimeter Activities for Your Math Lessons

Has this resource piqued your interest in our perimeter activities? Click below for more teacher-created, curriculum-aligned resources!

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Perimeter and Area Dice Game

Use this area and perimeter dice game as a math center activity when teaching area and perimeter to your 3rd and 4th graders.

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Perimeter Worksheet

Use these perimeter worksheets in your math lessons when teaching your students how to apply various formulae to calculate the perimeter of shapes.

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Perimeter Anchor Chart

Use this perimeter anchor chart to teach students how to find the perimeter of shapes such as squares, rectangles, triangles, hexagons and parallelograms.