Flashcards can often take the role of playing cards in the classroom. Design a set of flashcards that teach students the relationships between English units and the metric units. In this set of cards should be a series of matching pairs. What you want students to match depends on your goal of the lesson. You may simply want to know what units measure what; in such a case you may consider making card pairs like “Celsius” and “Temperature” or “Celsius” and “Fahrenheit.” In other cases, for upper-level students, you may want the student to demonstrate their knowledge of unit conversion. In this case, you would make card pairs like “F = ((9/5) * C) + 32” and “C = (5/9)*(F-32)”. For the game, you can run a matching game, a memory game or a find-and-seek game in which students must find the hidden cards in the room that match their cards.
One method of teaching is through student exploration. You can create a game of this by giving pairs of students two measuring devices: one in metric units and one in English units. Have the student pairs go around the room, measuring different objects and recording their measurements. The students should end this activity by inferring the relationship between these two units of measurement. For example, students would look at lists of object lengths and try to infer from their data the mathematical formula to convert centimeters to inches.
One fun lesson is an immersion activity. One day in class, tell students that you will only allow metric units in class. Then go on with the day as usual, but purposefully add some activities in which students will have to express measurements -- filling out questionnaires with their heights and weights. Students will have to reorganize their thinking patterns to deal with the novelty of using a new system of measurement.
Estimation games and contests can draw in student interest. One classic contest of this sort is to fill a strangely shaped container with a desired object, such as a beverage or candy. Tell students that whoever guesses the correct amount in metric units, such as cubic centimeters, wins the object. This activity is best run after a lesson on metric units, so that students already have a base in the metric system.