Now, tape the dime to the sharp end of the pointer, just barely leaving the tip of the pointer visible so you can take your measurements later. Then, glue one end of the hair to the pointer about halfway between the dime and the thumbtack. Allow the glue to dry. Now, holding the pointer still so it points straight to the right, pull the hair straight up and glue the loose ends to the mounting board near the top. After allowing the glue to dry, hang your hygrometer with the pointer at the bottom pointing to the right. Make a mark on the mounting board where the tip of the pointer is located.

On a day of high humidity, the hair will be slightly longer, so the pointer will point slightly lower. On days with lower humidity, the hair will be slightly shorter, so the pointer will point slightly higher. Make your daily observations by using a ruler to measure the distance from the mark on your mounting board to where the pointer is that day.

Thermometer

You probably already know that a thermometer is an instrument to measure temperature. To make your thermometer, you'll need a small bottle with a narrow opening, a clear drinking straw, some water, and food coloring. You'll also need some more modeling clay or Silly Putty® (chewing gum won't work well this time).

To start, roll your clay into a "worm" a few inches long. Wrap this around the drinking straw, right in the middle. Set aside.

Now, fill the bottle halfway with water, then add a few drops of food coloring and stir it up. Fill the bottle with water the rest of the way, clear up to the brim. (You may want to work in the sink for this part so you don't spill the colored water on the carpet!) Take your straw with the clay wrapped around it and place it in the bottle. Press the clay tightly around the straw and the mouth of the bottle to form an airtight seal. Be sure to press the clay down into the mouth of the bottle a little bit. This will force some of the colored water to rise into the straw where you can see it. Use a black marker to carefully mark the water level on the straw.

As the water in your thermometer heats up, it expands and forces the water higher in the straw. As the water cools down, the water takes less space so it falls lower in the straw. Since the outside air must heat or cool all the water in the bottle, you'll get faster, more accurate readings with a smaller bottle that contains less water.

Your thermometer isn't calibrated to actually tell the temperature in degrees, but you can still take observations by measuring the water level with a ruler. Place your thermometer in a safe place outside, out of the sun. Bring it inside if freezing temperatures are expected--it will burst if you allow the water to freeze. The thermometers you buy normally use mercury to allow them to measure temperatures lower than 32 or higher than 212, which are the limits for your water-based thermometer.

Weather Journal

You'll need a journal to keep your weather observations in. Each day, write down the observations you measure from your new weather instruments, along with a general description of the current weather conditions and your predictions for the following day.

After a week or two, compile your observations into a table or graph to see if you notice any trends. Before long, you should be able to make general weather forecasts using your own homemade instruments!

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Matthew Lewis, a homeschool graduate, is the web developer, and occasional columnist, for Home School Enrichment Magazine. Matthew is a self-described computer geek who enjoys doing things during his free time which he says would sound much too boring to be mentioned here. You may contact Matthew at matthew@HomeSchoolEnrichment.com

This article was originally published in the Mar/Apr '07 issue of Home School Enrichment Magazine. For more information, visit http://HomeSchoolEnrichment.com