I teach high school and I shoot a lot of things for the high school year book. This includes sports, drama, assemblies etc. I use several lenses but my goto optic is the SMC K 200/2.5 on my K10. It is fast enough for indoor work and great for sports such as football, soccer etc.
Rugby
Auditorium
Football
Of course, a zoom would probably be a better fit for most. I love the K 200/2.5 but I'm willing to admit MF isn't for everyone. At some point I would like to get a DA* 50~135. I think it would be ideal for most of the situations one would encounter shooting in a school situation. Mate it with the DA* 16~50 and you would have coverage for almost every scenario. They are more than fast enough and IQ is great.