Reciprocals: Flip Them!

Lesson Plan - Get It!

Audio:

Reciprocal.

Say it out loud a few times (Ree-SIP-row-cal). It really is a fun word to say!

A reciprocal is simply what we take times a number to get "1," and it is VERY easy to find.

Reciprocal may sound fancy; however, all that it actually means is to turn a number upside down.

Here are a few examples:

• Do you notice anything from these examples?

Take a look at the examples that are not fractions, those that start with a whole number (4 and 22).

• What do you notice is similar about their reciprocals?
• What about the ones that start as fractions?
• Do you notice anything about their reciprocals?

Hopefully, you have noticed that to get a reciprocal, you do one of two things:

1. For whole numbers (4 and 22), you simply put the number under 1.
2. For fractions (½ and ¾), you simply "flip" the fraction so that what was the numerator (the top number) is now the denominator (bottom number).

There are no catches and no extra tricks — that is it!

You will use reciprocals in math when multiplying and dividing fractions, so it is a great (and easy) skill to learn now.

Before you get to practicing, let's take a quick look at one thing.

• What do you get when you multiply a number times its reciprocal?

As you can see, each number times its reciprocal is "1." This is because a reciprocal is a multiplicative inverse of a number. A multiplicative inverse is what we multiply a number by to get 1.

• See how the definition of reciprocal and multiplicative inverse are the same thing?

That is because a reciprocal is a multiplicative inverse!

Now it is time for you to try your hand at flipping numbers to find the reciprocal!