Each student will be given identical sealed boxes containing a marble and a wooden block which has been glued in place. (The shape of the block will be simple for beginners and more complex for more experienced students.)

You can roll the marble but cannot look inside the box. Each student can draw a picture depicting what they think the shape of the block is.

Compare pictures with other students and each of you try to refine your drawings. Discuss how it is possible to describe an object without seeing it.

Scientists, in a similar way, make inferences about things they cannot see; such as atoms, the interior of the earth, phenomena in outer space (such as quasars).

Now your teacher will provide each of you with identical empty boxes, some blocks, and a marble. Try to construct a box just like the sealed one. Scientists often construct models to see if the models behave in the same way as phenomena they observe indirectly.