Design a set of 20 cards: The size, shape, and design on the backs of the cards is up to you, with one condition: when you lay out the cards, they must tile the plane (fit together perfectly without gaps or overlaps).

Write on the faces of 10 of the cards:

The diameter of a penny in mm

The radius of a CD-ROM in cm

The length of a pencil in cm

The height of a student in cm

The width of a classroom in m

The width of a classroom in m

The perimeter of a classroom in m

The area of a sheet of paper in square cm

The area of a table top in square m

The floor area of a classroom in square m

Create 10 matching cards by measuring the diameter of a penny, the radius of a CD-ROM, etc. and writing the measurement on a card face. Don't forget to include the unit names (mm, cm, etc.)

Use your deck to play a game of Metric Concentration:

a) Shuffle the deck and lay out the cards face down.

b) Each player turns 2 cards face up. If the cards match, the player collects them; if not, they are turned face down.

c) Continue until all cards have been collected. The player with the most cards wins.