Even though young students in the preschool classroom can compare big and small or long and short, it isn't until the early elementary years that they are ready to tackle customary units of measurements. During and after the second grade year students are ready to begin using rulers, yard sticks and other tools to compare standard sizes. Hands-on activities help your students to learn about inches, yards and miles.

Play Eye Spy

Asking students to suggest different ways to measure an object can help them to better understand customary lengths, according to the website Discover Education. Give your students a few different measuring tools, such as a yard stick, a tape measure and a ruler. Invite them to inspect, explore and experiment with the tools. They should look at the numbers and marks on the tools. Next, they can try out the items and make measurements of different objects around the classroom. When they start to connect the length and the quantity you can begin the "Eye Spy" game. Call out, "I spy with my little eye..." and finish the sentence with an object such as a desk, the white board or a book. Have the students estimate the length in the proper units. For example, your say, "I spy with my little eye a pencil." The students may say, "Six inches" or, "Half a foot." Ask the students to pick an appropriate tool and measure the object to check the estimate.

Let Them Jump and Throw

Even though you don't typically allow your students to jump around the classroom or throw objects, doing so can make for a fun-filled length lesson. An in-class long jump can help grade school students to estimate and make measurements, according to the University of Houston's lesson plan "Measurement Teacher Activities." Turn these types of activities into a math Olympics. Set up different events, such as a long jump, baseball throw or bunny hop. If you can't create a clear, obstacle-free area in your classroom, go outside. Use a piece of masking tape to make a start line. Have each student jump, throw or hop from the line. Ask another student to mark the end point with a piece of yarn. The jumper or thrower must estimate how far she moved in inches, feet or yards. Have her make the actual measurement afterwards. Keep a score board, writing the estimates and measurements on poster paper. Award gold, silver and bronze medals for the top jumpers, throwers, hoppers, and for the students who got estimates that were closest to the real measurements.

Measure Out Mega Objects

Instead of measuring objects to find the length, start with the length and "measure out" the size. Young grade school students may not have the conceptual ability to readily understand what a larger customary unit of length looks like, according to the article "Measurement of Length: How Can We Teach It Better?" in the journal "Teaching Children Mathematics." Measuring out distances can help your students to connect customary units with real-world dimensions. Connect the measuring activity with something that your students are learning about in class or an item that is interesting to them. For example, you are talking about dinosaurs in science. Go outside to a large, open space in your school's yard. Have the students use measuring tapes and other tools to measure out the height of a T. Rex -- 23 feet -- or the length of an Allosaurus -- 40 feet. Another option is to use yards instead of feet.

Give Them a Purpose

Out of context, an inch or a foot may mean little to nothing to your students. Make the customary units of length meaningful with a real-life indirect comparison, suggests professor of early childhood Constance Kamii in "Teaching Children Mathematics." Instead of assigning your students random measurements to make, give them actual examples to play with. For example, if you are working on inches and feet ask your students how many inches wide a piece of poster board can be to fit out the classroom door without turning it. Have the students pretend that they are making projects that have to stay flat in the poster board. They must measure the board and the doorway to come up with the correct fit. Put a further restriction on the activity and challenge them to make the board as long as they can without it hitting the door-frame. Measure the frame in feet and have the students convert it into inches to create pieces of poster-board that fit. The students who get the closest without touching win.