# What is an Array? Repeated Addition Arrays with a Simple, Cheap Manipulative

Updated on June 26, 2012

## Arrays

What is an array?

An array uses symbols to create rows and columns

Arrays can help people count or multiply more easily.

Instead of counting objects one by one, we can organize the objects into equal groups and count the groups. Think about skip counting, By 2’s 2, 4, 6, 8, 10 or How about by 5’s 5, 10, 15, 20, 25.

I am starting today with an easy, cheap manipulative that can be used at home or in a classroom. Pinto beans! I can put together multiple class set in a 2lb bag that costs about 2.50, less if I had shopper smarter. Today I was in a hurry because I am also using today's lesson for a job interview tomorrow (wish me luck).

So the first thing I did was count 25 pinto beans into a bag for each of my students.

We see arrays all over the place without even realizing that we do. We see arrays at the grocery store. An egg carton is actually an array. The carton has two rows and six columns. To make an equation 6 + 6 = 12 or 2 x 6 = 12. Just like the array made from pinto beans on the right.

That is a rectangular array, because it is in the shape of a rectangle. We can also make a square array, but remember a square is always a rectangle so it is still a rectangular array also.

The 3 by 3 (think 3 rows by 3 columns) creates two equations

addition 3+ 3 + 3 = 9 or

multiplication 3 x 3 = 9

As always remember that repeated addition is the same as multiplication - they are related like sisters, they don't always look the same but the come from the same family and they have the same answer.

You can draw arrays, create them with different objects, or see them within everyday items.

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