WHAT is a division array? 3rd grade math. I am a secondary math teacher and never heard of this.?

It's a visual way to represent a division problem by grouping.

For example, here's an example of:

12 ÷ 4 = 3

Do a web search on "division array method".

It looks to me like inverting multiplication using rows and columns.

To multiply MxN you set up an array of <object> with m rows and n columns. Then you can unstring the array into a line and count out the result.

This generalizes multiplication as repeated addition.

To divide you start with a string of D objects. You drop them into columns each with d rows. Q is the number of columns with remainder R left over.

You can also do this with numbers as well by essentially doing trial divisions of parts of D. You end up with place value based division.

This generalizes division as repeated subtraction.

HTH.