## Water and Thermometers

My son asked me whether you can make a thermometer using water. Of course we both realized that if the temperatures fall below freezing, the water would expand and could potentially break a glass, bulb-type thermometer. We also found various other suggestions, such as water doesn't respond as much to heat because of it's high specific heat index (how much heat it can take before it begins to get hot), to the fact water does not expand in a linear relationship to temperature (don't you love physics?)

Here is a YouTube video that shows how to make a simple thermometer. At the end he discusses why he uses alcohol rather than water.

We also found some explanations about a thermometer which may be filled with water called "Galileo's Thermometer."

Here is what one looks like. (Photo from Wikimedia Commons, see Galilean Thermometer link below) Isn't it beautiful?

This Galilean Thermometer link is a very clear explanation of how they work.

Fun alert: Arizona's Geotechnical, Rock and Water Resources Library link shows a graph of the density of water versus temperature to show that the relationship is not linear. But they also have a cool interactive illustration further down the page which allows you to change the temperature and see how the glass bottles move up and down. Have fun.

And finally, you might want to take a look at this activity using thermometers I wrote that is over at the Leaping FromThe Box website.

` Amazon.com Widgets`

## Wondrous Water

With the summer months upon us, it is time to think of swimming pools, sprinklers and beaches. Let's celebrate by doing science experiments with water.

Water truly is a wondrous substance. You could spend months, even years, studying water and its special properties. Although it is easy to take it for granted because it flows out of the tap, water is important to life and precious, too.

Physics Experiments
1. Friction
All you'll need for the first experiment is a surface that can get wet, such as floor, patio or counter top, and a few wooden blocks or flat bottomed toys. Slide the blocks over the dry surface first. Ask your children to think about how it feels. Is it hard or easy? What happens when you push the blocks quickly back and forth? Do they get warmer on the bottom?

Once the children have gotten a feel for blocks on a dry surface, pour on some water. Is it easier or harder to push the blocks around? Do the bottoms of the blocks get warmer or do they stay cool?

If your children seem interested still, you can ramp it up a bit (sorry, pun intended) by building what is called an inclined plane and allowing the blocks to slide down. A child’s slide would work great for this. You can even race blocks on a dry surface versus blocks on a wet surface. Have fun!

2. Floating and sinking
A classic water experiment is to examine what floats and what sinks. Fill the bathtub, a bucket, kiddie pool, or plastic bin with a few inches of water. Provide your children with age-appropriate objects to test, such as wooden blocks, coins, lumps of clay, and strips of aluminum foil. Believe it or not, what seems mundane to adults may fascinate a child, so be open to revisit this experiment and to test many different objects. Ask them to predict what will happen before the object goes into the water. Older children may be ready to learn about terms such as density and buoyancy.

Note: For safety, always empty the water out of the container after play and always watch children around water.

Chemistry

States of Matter
Water exhibits all three states of matter (solid, liquid, gas) at relatively normal temperatures and thus is ideal for studying these properties.

Solid:
Put some water in different-shaped containers (margarine bowls, food molds) and freeze it. Allow the children to help pick containers and fill them. For added enjoyment, add a few drops of food coloring to the water. Or you can add bits of edible flowers such as roses, or leaves of herbs as decorations

On a warm day, take the ice outside and use it to build ice sculptures. Remove the ice from the containers by briefly immersing in water if it won't just slip out. If you don't have time to make special shapes, simple ice cubes can work great for this, too. I have been told you can use salt to melt two pieces together, but I've never had much success with doing that. Pile the ice into buildings, animals or abstract forms. You can lightly mist the finished products with water containing food coloring. Then watch the sculptures melt. Predict how long it will take.

Older children can design inventions to protect the ice from melting, and then build and test their invention by seeing how long it takes for the ice to melt inside the device versus unprotected.
Enjoy the cool.

Liquid
You can perform many fun experiments with liquid water, such as seeing how many drops of water will fit on a penny. Dissolve salts or sugar into water. See how oil and water don't mix. You can study the movement of water in a straw, the possibilities are endless. Try this page for detailed instructions about testing oil and water.

Gas
To study water in the gas form, you will need water, paint brushes and a sidewalk or driveway on a hot day. If you must stay indoors, a chalkboard will work too. Simply paint the water onto a flat surface and then time how long it takes to evaporate. Explain that the liquid water is turning into a gas as it disappears and is rising up into the air.

To show the gas water turning back into liquid, set out a glass full of ice water on a warm day. The gas should condense into liquid around the outside of the glass after a few minutes.

Biology
Water is essential for life on our planet. We all know we must water plants for them to grow. But what are plants doing with that water?

To test this question, on a warm sunny day, slip a plastic bag around the end of a leafy branch of a tree and tie it tightly to the branch, effectively bagging the end to the tree branch. Visit the tree in fifteen minutes and then again in a half hour. What is happening inside the bag?

You should see the bag start to fill with condensing water. Trees release a lot of water on a hot day through a process known as transpiration. You are capturing the water that is being released.

You may also want to visit a pond, lake or ocean and observe all the living creatures that use water for a home. And hopefully you can do some wading or swimming to test the water yourself.