How to Teach Kids about the Pythagorean Theorem?

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The Pythagoras Theorem is one of the most important formulas in math, and kids are expected to grasp it by the time they get to middle school. Before learning the actual theorem, students must become conversant with a right triangle’s anatomy.

The Right Triangle

A right triangle comprises one ninety-degree angle on the triangle’s inside. In math, this angle is often marked with a box. The knowledge of all sides of the right triangle will make it easy and possible for children to understand how the Pythagoras Theorem works.

So, a right triangle forms a 90-degree angle. This type of triangle comprises three sides. The side that faces the 90-degree angle is known as the hypotenuse. Out of the triangle’s three sides, it is the odd one out as it is not part of the 90-degree angle. To learn about different types of triangles, consider offering your kid reputable online math courses that cater to students in different grades.

The Pythagoras Theorem

Named after the famous Greek mathematician Pythagoras, this theorem is among the most important theorems in modern mathematics. It outlines the way the different sides of a right triangle are related and is often applied to find a missing triangle side.

The hypotenuse always represents the longest side in this type of triangle. The other two legs (the two sides converging to form the right angle) are both short compared to the hypotenuse. One of the math tips kids can use to remember the two shorter sides would be looking at the letter “L” that is formed when you trace the triangle. The “L” represents the legs.

If a child is having trouble establishing which side is the hypotenuse, guide them to draw a line from the square marking the 90-degree angle up to the opposite side of the triangle. The newly drawn side is the hypotenuse. To allow kids to practice material, look up “math help for kids” to find math websites that make the concept more digestible for kids.

Pythagorean Theorem

The Pythagoras Theorem states

The area of the square whose side is the hypotenuse is equal to the sum of the area of the squares whose sides are the legs at a right angle.

As a result, the following mathematical formula is true:

 a2 + b2 = c2

 In this formula,

  • a, b, and c represent the three lengths of the triangle’s side
  • c stands for the hypotenuse, the side opposite the triangle’s right angle
  • a and b are the legs that form this 90-degree angle.


A common mistake made during learning math for kids is assuming that the hypotenuse is always the slanting side. In reality, that is not always the case; instead, it depends on how the triangle is drawn. By just flipping the image, a different side other than the hypotenuse might be slanted.

There is a simple way to quickly identify the hypotenuse regardless of how the triangle has been drawn. Teach a kid to train their eyes to look across from the square representing the 90-degree angle.

Key Things to Remember when Learning the Pythagoras’ Theorem

When kids learn about the Pythagoras’ Theorem, here are some key things they should keep in mind:

  • The theorem exclusively applies to right triangles. These are types of triangles with a 90-degree angle.
  • The hypotenuse is the side opposite the triangle’s right angle.


Although the Pythagoras Theorem is an important topic covered in mathematics for kids, it is relevant because it also has real-life applications. For instance, it is applied in constructing structures like support beams and calculating distance during surveys. When teaching this theorem, the use of images of different right triangles will make the lesson more fun and easier to understand.

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