• Study Sessions – Library, Great Hall, Corridors, Common Rooms
• Reading anywhere basically
• Flying practice and playing quidditch with a few friends for fun
• Baking, cooking, sewing and crafting in the Homemaking Magic room
• Make music or dance in the music room
• Create art in the art room
• Brew some potions for your personal stock
• Poke around and explore, play pretend and wear costumes
• Talk to ghosts in the dungeons
• Talk to paintings
• Sleepovers and impromptu house parties in the common rooms
• Play some (harmless) pranks, don’t be shy – but confuse, don’t abuse!
• Practice your spellwork in the dueling room or in common rooms, practice dueling with friends?
• Tea and picnics with friends!
• Seasonal activities! Prepare for upcoming holidays and take advantage of the weather – ice skating, swimming, snow related activities, leaf piles, etc. 
• Bubble yourself and roll around!
• Races on brooms and on foot!
• Play with your pets! Have pet playdates!
• Tend to the owls in the owlery
• Make Owl Post deliveries! 
• Play games! – Exploding snap, gobstones, wizard’s chess, and more!
• Test your skills with herbology and care of magical creatures! Visit the greenhouses or explore the grounds, and try to identify and care for things
• Extra credit activities – Compost, assignments, art projects, cleaning, etc.
• Trade things with each other or become an entrepreneur and sell stuff to your classmates!