Potato Race is from WebTennis24.com. Why they have named it Potato Race I do not know, but since they have taken the trouble to name their game, I will respect that!
Place small piles of balls at the net, one pile for each player. Players begin at the baseline. They run up to the net, get one ball. Run back to service line, bounce feed ball over net. If they are successful, they run back to baseline and repeat until all balls in their pile have been hit over the net. If they miss into net, they retrieve ball and try again. First player to get all balls in their pile over successfully and return to baseline is the winner.
I would adjust the rules based on the ability of the player. For very young beginners I would relax the rules and allow any ball over net whether it is in or not. I would also consider having them just throw the ball over the net if they are very young. For my older players I would expect their bounce feed to be hit into play. However with this game there is not a simple way to have them retrieve a ball that has been hit incorrectly over the net (out of play) so not sure how to handle that.
Also if your older students are like mine, you will need to remind them this is a bounce feed, not a serve or overhead slam or volley.