Split your class into two teams. Give each team a list of items in the classroom that must be measured, either in inches or centimeters. Examples of some items may be a marker, an eraser, the width of a desk or the distance from the front door to the teacher's desk. Be sure each student has a ruler and understands how to take basic measurements before beginning this game. Explain that the first team to finish the list of measurements correctly will win a small prize, such as stickers or a bookmark.
Once students are confident using a ruler and understand the basic principles of linear measurement and length, try playing an estimation game. Show the students three objects, such as a pencil, a banana and a piece of chalk. Ask the students which item they believe is 10 inches long. Have each child write her answer on a piece of paper. Once every child has written down an answer, ask a child volunteer to come up to the front of the room with a ruler and measure the three objects. See how many students guessed correctly, and offer a small prize for answering correctly, if you wish.
Use this game to show children that one foot equals 12 inches and that one ruler equals one foot. Ask a linear measurement question, such as "How many rulers will it take to measure from the bathroom door to the water fountain?" Place masking tape on the floor from the bathroom door to the water fountain and ask children to use their rulers to measure along the tape. Each child can lay down a ruler along the tape, and then count the number of rulers it took to measure the distance. Explain that this number is the number of feet in the distance from the bathroom door to the water fountain. Explain that in order to find the number of inches in that distance, you will need to solve a simple multiplication problem. Explain that each foot is twelve inches, and that by multiplying the number of rulers by 12, the students will know how many inches in the distance between the bathroom door and the water fountain.
Similar to the ruler race game, the measurement scavenger hunt will be a bit more challenging. You may split the class into cooperative small groups for this activity. Give each group a list of measurements, such as 14 inches, three feet or 28 centimeters. The students must work together to find items in the classroom, or distances between two points in the classroom, that equal the measurements on their list. In order to make this game a little simpler, you may choose to make it a multiple choice activity. For example, list several possible answers for each measurement and allow students to use their rulers to find the correct answer. Offer a small prize for the group that completes the list with the correct answers first.