How to solve for a missing side in a perimeter problem
In short: When a geometric shape is missing a measurement, you can still find its total boundary. This video demonstrates how to use logic to identify and calculate unknown side lengths.
The lesson focuses on 3rd-grade geometry, moving beyond basic addition and subtraction of 2-digit whole numbers. Students learn to calculate the perimeter of a figure even when one side length is not explicitly provided.
This skill serves as a bridge to more complex concepts like multiplication, division, and fractions. It encourages learners to use the properties of shapes to deduce missing information, a foundational step toward mastering area and place value.
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Sources
- Summary by Intellect · source: Finding perimeter when a side length is missing | Math | 3rd grade | Khan Academy
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