Give each student a small paper cup with salt water in it. Ask them to taste it and describe what it tastes like. Point out that while our planet is mostly water, most of the water is salt water and not fit for drinking. Lead them in an experiment that makes salt water drinkable. Start by writing the word "desalination" on the chalkboard.
Fill a large bowl with about two inches of salt water. Make salt water by stirring salt into water until the salt dissolves. Put an empty glass into the center of the bowl. The rim of the glass should be above the water but below the top edge of the bowl. Tightly wrap plastic wrap over the top of the bowl and tape it down. Put a small rock on the plastic wrap directly over the center of the glass in the bowl. Put the bowl, which is now a solar still, in the sun for an entire day, checking on it throughout the day. Point out any condensation on the plastic wrap. After a day, taste test the water that has dripped into the empty glass.
Choose one city anywhere in the world for each student in your class. Write the name of that city on a piece of paper and then have everyone draw a city randomly. Tell them that they are going to adopt that city for a year, a semester or a month, depending on how long you want the unit to last.
Each student needs to find her city on a map. Then show the students how to look up their cities' weather using the Internet. Tell the students they are going to check the weather in their adopted cities every day and record it in a weather log. Once a month, have them create a graph that communicates weather patterns in their city.
Explain to students the role that glaciers played in carving the land forms throughout the world. If possible, show them a map of glacier movement for your home state. Have students freeze gravel or pebbles in a paper cup filled with water overnight to create a model glacier. Tear the paper cup away and then have the students use their model glacier to move over dirt, pebbles or wood chips and observe the effect it has.
Give each student a map of the world that contains latitude and longitude markings. Have them visit a site that tracks earthquakes for the past seven to 30 days. Then have them plot the location of each earthquake on their maps and put a dot wherever the earthquake occurred. After they have collected a month's worth of data, discuss as a class any patterns they noticed and what they observed.