So my boys wear uniforms to school. Navy blue pants and white or light blue polo shirts. My boys play hard and blow out the knees of their pants. When I first notice the material getting a little thin, or there is ust the tiniest of hole starting, I apply patches - on the inside. Patches on the outside are not acceptable uniform attire. This buys us a little more time. I use this especially in March and April. As of April, tailored shorts are acceptable uniform attire. Yes, since I do sew, I cut off the holey knees, hem them and we have a great pair of pants.
I use iron patches and then stitch around the edge. Yes you can see the stitching line, but the teachers at school have never made an issue of it. Most of them are Moms too and understand, especially come April or MArch.
The shorts thing works for us becasue DS11 is very thin and long-legged. Even slim sizes are usually large in the waist for him.
Hop on over to Shannon's site for more great tips.