Draw/write something on the piece of paper.
Place the drawing behind the card so that it is not visible.
Find the place to hold the mirror so that you can see around the card at your drawing.
Stick the drawing on the underside of a table.
Find the place to hold the mirror so that you can see under the desk at your drawing.
Play around with other ways of using the mirror to see around corners/behind you etc.
Make a periscope
Gordon Elementary Science Club