### Why do this problem ?

This important

problem
will lead to a thorough understanding, and demystification of, the
various units which exist. Students will enage in a variety of
problem solving strategies in its solution.

### Possible approach

This question initially appears to be quite demanding. Provide
a printout of the data to each student. Which units are already
known? Suggest that these first be crossed off, with the results
tabulated elsewhere. This will significantly reduce the scale of
the problem.

### Key questions

Are there any obvious pieces of data with which to start?

### Possible extension

Extension activities are given in the question. Can students find
examples for each of the units?

### Possible support

Create cards for a team card sorting exercise, allowing
students to move the various data around physically.