You can show how the time zones were established using a globe, a few pushpins and a flashlight. This can be done in front of the class, or if you have several globes and flashlights, you can break the pupils into groups for this activity. Push several pins into the globe in different time zones. Explain that the time zones exist so that at noon the sun is highest in the sky for that area. Dim the lights and shine the flashlight over one of the pushpins. Explain to the pupils that the flashlight represents the sun. Explain that the people at the pushpin under the light would see the light in the middle of the sky. Ask the pupils how much light the people at the other pushpins see at this time.
Print a time zone map (see Resources). Using an analog clock, explain that the 12-hour clock divides the day into a.m. and p.m. The dividing line for this clock is noon, when the sun is highest in the sky. Tell your pupils that many people in other countries, and people who must look at what time it is in many places, use a 24-hour clock. In this clock the a.m. hours are the same as in a 12-hour clock, but the p.m. hours are the 12-hour-clock hours plus 12. So 8 a.m. is 8:00 on the 24-hour clock, but 3 p.m. is 15:00 on the 24-hour clock.
Explain that the 24-hour clock can be useful because you don't need to know if it is a.m. or p.m. Point to a time zone on the map and tell your students a time for that time zone. Ask them what that time would be on the 24-hour clock. Ask them what time it would be in a different time zone and then what time that is on the 24-hour clock.
Have children construct paper plate clocks by numbering the edges of the underside of a paper plate. Have them cut out two clock hands, one larger for the minute hand and one shorter for the hour hand. Have them use a paper brad to attach these hands in the middle of the plate.
Split the class into groups and assign a time zone to each. Explain to the pupils how many hours separate the groups. Tell one group a time to show you on their paper plate clock. Ask the other groups to figure out what time it would be in their "time zones." You can also ask them to convert between the 12- and 24-hour clocks for an additional challenge.
Show pupils a map of the time zones (see Resources). Tell the class that someone is traveling from one time zone to the other. Tell them at what time the person left, which time zone they are going to and how long it took them to get there. The pupils will need to add the time spent traveling, and then add or subtract time for the adjustment in time zones. This can be used with the paper plate exercise and the two time scales exercise as well.