Read a text book, or story book about the earth's rotation. One picture book that you can read to young children is "What Makes Day and Night" by Franklyn M. Branley.
Place a sticker on a globe on the area where the students are located. If they are old enough, have them find this spot for you, otherwise, tell and show them where it is.
Turn off the lights in the room and turn on a flashlight. Point the flashlight at the globe where the sticker is. Ask the children if they think it's day or night where the flashlight is shining.
Turn the globe so it rotates on its axis, stopping when the side of the globe opposite the sticker is illuminated. Ask the children if they think it's day or night where the sticker is.
Rotate the globe to bring the sticker back into the light. Explain to the children that this is how the earth rotates, and it takes 24 hours for the sticker to completely spin around.
Hand each child an apple, a sticker and a toothpick. Tell them the apple is the earth. Instruct them to place the sticker in the same approximate place on the apple as you did on the globe.
Tell the children to push the toothpick halfway into the bottom of the apple so it can spin on its axis. Give each child a flashlight and have him repeat the demonstration you did with the globe.