Have students create a plastic beaker or measuring cylinder from a large plastic pitcher or glass jar. Instruct students to pour American (fluid ounces, pints and quarts) and Metric measurements (milliliter and liter) into the container and draw parallel lines on the pitcher with a permanent marker, indicating the measurements. Display liquid measurements at the front of the room -- for instance, a cup of coffee labeled "6 ounces" -- and have students guess the Metric or American conversion without using a formula, to practice gauging approximate conversions. Display a large volume, such as gallon, and have students calculate how many small units (milliliters, for instance) it takes to equal a gallon.
Give students the weights (in grams, ounces, kilograms or pounds) of different objects from around the classroom and have them calculate the conversions from grams to ounces and kilograms to pounds. Assign students to weigh various objects at home, such as three cans of soup, a heavy book or a cooperative pet; challenge students to come to class prepared to give both American and Metric weights for ten objects found at home. For additional practice, have students calculate the number of smaller units (grams or ounces, for instance) in larger weights, for instance, have them calculate the grams, ounces, pounds and kilograms in a box of books.
Provide students with formulas to convert basic length measurements. Play bingo, having students mark on a bingo card the answers to measurement conversions. For instance, give the clue “1 inch” for students to mark the box “2.54 centimeters.” Use the same answers to create each card, but scramble them so that no two bingo cards are the same. Have students create their own measuring tapes with American and Metric system measurements marked on each side, respectively. Give students word problems to solve using distance conversions. For instance, ask "Sarah ran six miles. How many feet and kilometers did she run?"
Divide the class in half and have students approach the board two at a time (one student from each team). Give two measurements aloud, such as “1 ounce and 28.35 grams.” Have students mark the relationship between the figures, using the symbols for greater than, less than, or equal to, allowing them to use the board to manually calculate conversions; correct answers score a point for the student's team. Have student arrange measurements in order, such as "one ounce," "28 grams" and "one kilogram," from less to more to most. Divide the class in thirds and assign each group to compose a word problem based on liquid volume, weight or length/distance; create a worksheet of the students' word problems and make a copy for each student to complete in class or for homework.