If there's not enough space in your classroom for a hideaway, You can always create one. Here's a few ideas to get you started.
Place two chairs far enough apart that a sheet will fit over them both. Fold the sheet back enough that you can still see inside.
This little hideaway I created outside, using small chairs.
I used clothes pins to secure the sheet.
This big one I created inside using adult sized folding chairs.
The clothes pins are secured under the backs of the chairs.
And, this cute little structure was abandoned outside a church on the curb. I was more than happy to take it off their hands. It's made from PVC pipe. I keep it at my house, but I will occasionally bring to school to use as a hideaway.