Here was my room on the last day of school with table bins cleared and some items off of bulletin boards.
Check puzzles, manipulatives, & games.
I try to get the students involved if I can. The end of the year has lots of random assemblies and days where our schedule is a little funky. On one of those days we go through our puzzles. I assigned each couple of students a puzzle to put together and check that it has all of the pieces. If it didn't, I either threw it away or saved it for a project.
The puzzles went back into the cabinet. We also organized the other items inside. We went through other games and manipulatives too.
Organize your classroom library.
There are many different stickers and labeling systems that teachers use for their classroom libraries. Even if each book has a sticker on it to match a label, students will still get books in the wrong tubs. I had a few volunteer students go through each tub to make sure the books inside had matching stickers and tubs. This took maybe 20 minutes. If I waited till August with no other help, it would take me double the time.
Go through old supplies.
I know this isn't always the case, but some years we have extra supplies after we pass out any that is being sent home with students. This year our art teacher was looking for some pencil boxes. For some reason I had 4 or 5 in my room that I put in a bag to give to her. She also needed markers and we had some leftover with no names on the box.
I also plan to give to the office and some of our specials area our extra hand sanitizer since they do not get students bringing supplies to those areas. We use it a LOT in the classroom but for some reason always have a ton left.
Find ways to save yourself a little bit of time when you return back to your classroom and pick some helpful students. Go through and purge old supplies, games, books, etc to save you time and give you space!