This is something that I did with my class at the beginning of the school year. I plan on doing it again this year, I thought I would share.
First, I got out my huge hundreds chart! See THIS post for more on the hundreds chart.
We talked about what it looked like and what it could be. I asked them if it could be a hundreds chart and if it was a hundreds chart where would 1 be? They helped me number it. We wrote on it with a dry erase. I had kids go and stand on different numbers so that we could notice patterns (e.g. if you add 10 you will end up directly below the number you started at.) After we had explored the hundreds chart and numbers a little bit I gave each student some squares and assigned them numbers to write. We then put them all together to make our very own hundreds chart that was up in our classroom all year!