Problem:

In the rectangular prism below, all intersecting edges and adjacent sides are perpendicular.
 

1.   What is the shape of the face opposite side R that you cannot see?

2.   Put an X on two parallel lines on the rectangular prism.

3.   Shade two perpendicular faces the same color.

Answers:

1.   Rectangle

2.  

 3.   Answers may vary.

 Examples: