High school baseball rules situation help?

If the fielder is standing on the base, and the runner knocks him down, there is no illegal action. If the fielder catches the ball and steps away from the base to clear from the runner, and the runner slides into him, it is illegal, and interference is called. If the fielder was throwing the ball when the player slid into him illegally, it is interference and both the runner and batter are out. I'm pretty sure in high school, interfering with the guy on second is an automatic ticket to a double play. High school umps are all about protecting the kids, so don't be too surprised.