"Midnight Offerings" (1981) starring Melissa Sue Anderson, Mary Beth McDonough, Patrick Cassidy is a TV movie about witches in a California high school.
Vivian Sotherland (Anderson) is the head of the cheer squad and until recently she was going out with David Sterling (Cassidy), the football team's quarterback. The movie starts with Vivian dressed in a black robe in front of a dark shrine, chanting spells which end up causing their science teacher to die in a horrible car accident. That teacher was going to flunk David which would have got him kicked from the team.
David is cold to Vivian. He has figured out she is a witch and has put together a string of "accidents" that has got him and her to the top of the class. David wants nothing to do with her anymore. New girl, Robin Prentiss (McDonough) joins the school and meets David on the first day. They instantly take a liking to each other. Vivian of course will have none of that and she immediately starts her campaign of black magic against Robin. But something is not working - Robin is fighting back with her own magic that she is just discovering.
David and Robin grow even closer as bad things continue to happen to them. They seek the help of a local expert in witches, Emily Moore (Marion Ross) who does what she can to help Robin learn how to user her powers. She informs Robin that this is leading to a battle of good against evil and she better prepare in order to face the evil Vivian!
This is your standard made for TV horror movies of the 80s. If you want to stay in for a Saturday afternoon, this is a good one to watch.