Arduino Matrix

My computer science teacher and I are trying to make and program an led matrix, (possibly like 5 X 5 or a little bigger). We started off with a scrolling 1 X 5 led matrix, but that the letters were pretty difficult to read and it was too simple, so we moved on to a srolling 2 X 5 matrix. However, that was still pretty dificult to read and didn't look great either. Neither of us have much experience with the hardware for excedding the maximum number of output pins. We are basically at somewhat of a standstill with this project until we can either learn how to access or add more outputs, which I'm not even sure is possible, or learn how to use something like along the lines of an Atmega.  We would really appreciate it if anyone could give us some tips or possibly some instruction on this topic. Also, just for reference, I have the arduino uno. The original project for this class was going to be a small 3-axis arduino controlled cnc mill, but the hardware was going too demanding to do on my own. If anyone is interested in this project, please let me know. Thank you for reading this.

- Jeremy B.