WHAT TIME IS IT? Project: Make a World Time Zone “Clock”

Paper Plate Time Zone "Clock"

It takes 24 hours for Earth to make one complete revolution in space.  As each hour passes, Earth rotates approximately 15 degrees of longitude.  In 1884, at the International Meridian Conference, it was agreed to divide the world into 24 time zones measured from the Prime Meridian in Greenwich, England.
What time zone do you live in? You can make a time zone “clock” that will help you figure out what time it is in other parts of the world compared to the time where you live.

You will need:

• scissors
• 2 paper plates
• ruler
• pen
• brad

1.  Cut the rim off one paper plate to make a flat circle.
2. Use the ruler and pen to divide the circle into 24 equal pie-shaped sections. Start by dividing the circle into quarters and divide these in half to make eighths.  Then divide each of these into three smaller sections.
3.  Write “London, Greenwich Mean Time” in one of the sections.  Then, continue clockwise writing the name of a city in each of the following time zones.
4.  Place the circle with the city names in the center of the other paper plate.  Fasten them together with the brad.
5.  On the rim of the plate, above the pie section that says “London,” write “12:00 Midnight”.  Continue in a clockwise manner, writing 1:00am, 2:00am, 3:00am, and so on until you return to 12:00 Midnight.
6.  Look at the time on the rim of the plate above the time zone where you live.  That is what time it is when it is 12:00 midnight in London.  When you rotate the circle so that the time on the rim is your current time, the other pie sections will tell you what time it is in other cities in the world.

Note: If you need to adjust your time according to daylight savings time, remember: spring forward (add an hour in spring); fall backward (go back an hour in fall.)

You can find this project and many others in my book The Geography Book: Activities for Exploring, Mapping, and Enjoying Your World. It is available both in paperback and as a Kindle book.

Project: THE SALTY SEA, Making Salt Crystals

Salt Crystals

Ocean and sea water is salty.  Some lakes are also made of salt water, but most have fresh water.  Great Salt Lake in Utah, the Salton Sea in California, and Lake Nakuru in Kenya are all salt lakes.
You may have swum in the ocean or a salt-water lake.  Even though the water was clear, you would have been able to taste the salt on your tongue.  When salt dissolves in water, it disappears.  Here is an experiment you can do to make it reappear.

Making Salt Crystals
You will need:

• 1 cup sea water (If you do not live near the ocean or a salt lake, you can make your own sea water by mixing 2 teaspoons table salt with 2 cups [.5 liter] water.)

• pie pan

• magnifying glass

1. Pour the sea water into the pan.  Put the pan in a warm, dry place and let the water evaporate.  This will take a few days.  What do you see when the water is gone?
2. Look at the salt crystals with the magnifying glass.  What shape are they?  Each kind of mineral forms its own crystal shapes.  Can you see the X-shaped indentation on the top of each crystal.

About two-thirds of the salt that is dissolved in sea water is sodium chloride, or ordinary table salt. When water evaporates from the sea, the salt is left behind, just as it was in your salt crystal project.  This means that the water vapor in the atmosphere, which falls back to Earth as rain, is fresh water.

You can find this project and many others in my book The Geography Book: Activities for Exploring, Mapping, and Enjoying Your World. It is available both in paperback and as a Kindle book.