I have been in ele classes where they use real mirrors. Just put tape around
the edges and tape the backs (masking tape or clear packing works great).
This way if it breaks (yes I had a student break one of course) then you
don't have those little pieces everywhere. But mostly, if you put the fear
of YOU in them...<g>...then they will be extra careful!
PS...I did spend the money on those great double sided acrylic mirrors. The
little darlings have broken 7 of them!!!! They have just split in two!