Split the class into teams of 4-6 people. Each team stands in a straight line on a spot, with each team member roughly 5m apart.
A ball starts with the first person in line, they must throw to their next team member, who catches succesfully, turns and then throws to the next person, and so on. The winning team is the team who has thrown the ball down the line first, reaching the last person, and team is sat down.
All catches must be correct technique, catching in mit (if no mit, least dominant hand is fine), and then transferring to throwing hand.
After each round move around end people so every one gets a turn starting and finishing relay.
Modification can be to shorten or lengthen space between each person to make easier or harder.