Ask.
Generally, if they approached you, it should be free with a certain amount of images in trade for your permission model release.
But ask to be clear as to what to expect.
I used to do the odd model shoot when I was bored this way or knew someone they had a look I really liked. I would tlc a decent amount of images for the model and get a signed model release for piece of mind.
Boxing day many moons ago, pristine snow cover. Walked about 5 miles to a beautiful spot. Took my new camera out to take photos, you guessed it, battery was on the charger. Lesson learned, ordered a spare that night lol.
You're shooting two types of photos here in a way.
The sport and the students.
The sports side you will learn from looking at your work and others. Learning the sport, the action moment, where to locate yourself for the best images depending on your kit. Look close at your mistakes and learn from them.
The student side is getting pictures of the students on the sidelines and candid moments. Get group photos after the games, get smaller grp photos of friends circles. I've often found that these are more popular than the action shots.
You may find other togs in your area covering smaller teams and school shorts, look at what they charge for prints/digital and use that as a benchmark.
Good luck and enjoy.
Local demolition of a big shopping centre. Was taking some shots from behind the fence, and an official looking guy walked up to me and asked what I was doing. He then asked my name and said I thought it was you, you did my daughters wedding.
Five mins later I was in a hi-vis and helmet and given full access and he even had the vehicles give me time to get good shots. I had a great time.
Most of the answers for the wildlife side seem covered.
For landscapes I'm going to go slightly outside the box. I use a dji pocket for ease when I'm out and about and want to travel light. The image stabilisation is very good, good for panorama images, video abs time-lapse. And it's small and I find it fun. Just a thought.