I rememberd the book that I have, One Hundred Hungry Ants, by Elinor J. Pinczes. We read that together and used our little counting animals in place of ants. My older son thought this was so much fun and joined right in.
We started by counting out one hundred animals by placing them right on the numbers of the hundred chart.
In the book, the ants are on their way to a picnic. They are in a single file line at the beginning.
Here are our 100 animals in a single line:
Then the littlest ant decides that it would be quicker on 2 rows of 50- we split our row in half to line them up in 2 rows.
The book goes on- each time the ants line up in different ways that add up to 100. This concept was great for my 1st grader as he worked out the addition and multiplication problems that the book presented.
The last combination was 10 rows of 10.
Did the ants make it to the picnic in time? You'll have to read it to find out! :)