Kids are always asking in math classes, "Why do we have to learn this?" Now I have a specific and practical reason for learning square roots.
When simplifying multiplying square roots, for visual learners, I explain that they are simply finding the TWINS. In the above example, the twins are 5 and 5, since five times five equals 25.
I would probably set up a matching game on the board with square roots in one column, and doubles in the second column. I would ask the kids to take turns coming to the board to match up the twins to their "house" or radical. So the square roots of 4 would match with 2 x 2. The square root of 16 would match with 4 x 4. The square roots of 49 would match with 7 x 7.
When simplifying square roots (radicals), you need to tell the class that they need to look under the roof to see if the twins are hiding. In the example:
√18 this is not an exact square. So let's find the twins. The most obvious number to multiply to get 18 is 9. So you can tell the kids that the new square roots is