International Comic/Manga Schools Contest:
This is a manga, comic and illustration contest open to students worldwide. Winners are eligible for cash prizes, digital creation software, pen tablets, and chances to be featured in media publications. Entries must be for appropriate for all ages.
Online Video Contests: A great resource for all kinds of contests involving video. Many with cash prizes! The Yale 2020 Environment 360 Video Contest encourages the videographer to make an ingenious video, get a reward, & save some green! The Stay Home, Go Big: Open Call Video Project encourages people to recreate their favorite scenes & moments from movies & TV shows.
Write the World Contest: Every month is a new writing challenge. This month is poetry (as April is Poetry Month). The winning entrant receives $100, and the runner-up and best peer-reviewer receive $50.
Bulwer Lytton Fiction Contest: Just for fun... The Bulwer-Lytton Fiction Contest is a "whimsical literary competition that challenges entrants to compose opening sentences to the worst of all possible novels." The "official deadline" is April 15th but the "actual deadline" is June 30th.
Embracing Our Differences Art Contest: An art contest for all ages with the theme “enriching lives through diversity and inclusion.” Grand prize: $1000. Deadline: October 7, 2020.
Try TinkerCAD if you're looking for something for students to do which involves design and creativity, this free software from AutoCAD may be what you are looking for. Sign up for TinkerCAD as an educator and link to your Google Classroom. There are many applications and you don't need a 3D printer (although there are websites which will print your designs). Instructables has a contest currently for TinkerCAD as well as an educator's page.
Jigsaw Puzzles - Find a space or board large enough for 1000 pieces.
Exercise - Research how to do exercises for a certain goal, i.e. sit-ups in a minute, pull-ups, free weights, running a 5K (keep your distance from others). Track your progress. Challenge yourself and others!
Get Artsy/Craftsy - No excuses! Draw your pet, paint the great outdoors, learn how to create something watching YouTube. Or get one of those fancy paint-by-numbers sets.
Movies - Find a list of the best movies of all time and stream them.
Write - Get a journal and start writing. Poems, a diary of today's events, a short story, etc.
Music - Try a different artist/genre of music based on reviews.
Games - Play a game that doesn't need electricity like Sorry, Monopoly, chess, checkers, and so on.
Cook something - Browse online for recipes, watch a YouTube video, find an old favorite from your family, make a fancy dessert!
Try a new hairstyle - Do something totally different!