real science for today's homeschooler

How do colors affect temperature absorption?

How do colors affect temperature absorption?

We’ve all heard the fashion sayings . . . “never wear white after Labor Day” . . . “pastel colors should be worn at Easter” . . . etc. You know the traditions, but did you know they are actually based on science? The color of the clothing you wear can affect how hot or cold you feel when standing outside during the day.

The light reaching us from the Sun is known as “white light” and it is really made up of all the colors of the rainbow. Each of those light rays coming in contains energy. White materials reflect all colors away from their surface, absorbing none of the light energy. Similarly, light pastel colors reflect almost all the incoming light energy. Black materials absorb all light rays, allowing none to be reflected into our eyes. (That’s why it looks “black.”) Dark colors absorb almost all the incoming light energy.

So, you wear light colors in spring and summer to stay cool, and dark colors in the winter to stay warm. Fashion traditions are based on science! You can investigate this phenomenon with your children to prove that it works:

1. Select two t-shirts. Ideally, use one black and one white. If you don’t have black and white, use one that is as dark as possible, and one as light as possible. Also, select t-shirts that are similar in size and fabric type.

2. If possible, do the experiment outside on a warm, sunny day. Select a spot where you can lay the t-shirts out flat, side-by-side. Try not to set them on metal as this will affect the temperature.

3. If you have two similar thermometers, you can just insert a thermometer inside each t-shirt, wait for a select amount of time, and then read the thermometers. Try waiting about 15 minutes and then check for a temperature difference. Increase the time if necessary. Time will depend on the intensity of the sun that day.

4. If you only have one thermometer, try putting some water in two plastic baggies. Be sure to use the same type and size baggie, and the same amount of water. Place one of the baggies of water into each t-shirt at about the same place. Increase the time to about 30 minutes since it will take longer for the water temperature of the water to change noticeably. Be sure to check the temperature of the water in place. Bringing the water into the cool house can drop the temperature significantly while waiting to check the second bag.

To extend the experiment, especially for older children, repeat with different “medium” colors or prints to see what effect each has on temperature. You might also want to test how different types of fabric affect the absorption of light energy. Your children can then write their own “fashion rules” based on science!

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Testing the pH of Soap

Testing the pH of Soap

We usually think of soap as being a very mild substance that is good for the skin. But, the cleansing effect of soap is due, in part, to the fact that it is a basic substance. Some soaps can dry out the skin, or even damage skin with frequent use.

When you teach your children about acids and bases and the pH scale, have them explore the pH of different soaps in your house. Test bath soap, dish soap, clothes soap, shampoos, facial cleansers, etc. They can also test household cleaners you may use, especially those that contain ammonia. But be sure these harsher products are tested under adult supervision since ammonia products can be harmful if they get in the eyes or are swallowed.

The easiest way to test pH is with pH test strips. You can buy these anywhere swimming pool or pond chemicals are sold, but they are usually fairly expensive. Unless you want them right away, you can order universal pH paper strips here for a very reasonable price. The shipping is a flat rate so you might want to join with other homeschool families to put in one order together, or look around for other science supplies you might need in the future.

For thick liquid soaps, powders, or bar soap, mix with a little distilled water so that the test strips can absorb the chemicals. All pH test strip packages come with a color key that can be used to determine the pH. Very often the color of the test strip will be in between two colors on the key. Use this as an opportunity to teach your children about estimating between two known values.

After you have results, remind children that a pH of 7 is “neutral” and completely harmless. The farther away from 7, the more harsh, and potentially harmful the base. Discuss the relationship between the pH of different types of soaps and their intended use. Why is there such a difference between bath soap and household cleaners? Also, check to see if any of the products advertise themselves to be “pH balanced.” Based on the pH test results, what does that mean? Do those products have a different pH from other similar products that don’t make that claim? Finally, you can extend the results with a consumer finance application. Do you find a difference in the pH of similar products from different brands? For example, is there a difference between the pH of a name brand bath soap and a cheaper store brand?

One final word about using test strips. A universal test strip tests a wide range of pH values and so will have less of a color change between similar pH values. A more narrow range test strip will show a bigger color range between similar pH values, but will show no results outside of the range of the pH paper. So, if you buy narrow range test strips, be sure they are within the range you want to test. For example, if you are testing soaps you will need to use pH test strips that test for a pH range above 7. Acid test strips (that test below 7) will give no results when testing soaps.

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What is my Ecological Footprint?

What is my Ecological Footprint?

Our children have a very egocentric view of life and, through limited life experience, they typically assume everyone has the same type of lifestyle as they do. While we talk a lot about conservation, how do we really measure up to other people? As you study ecology and conservation with your child, go online with them to take one of two Ecological Footprint Quizzes to reveal the size of your family’s ecological footprint. The first EFQ is very visual and fairly basic and simple and would be the best for younger children. The second EFQ is more in depth and would be great for older children.

The results that come up from the first quiz will reveal several interesting facts . . . and they may surprise you! How many acres of land are needed to sustain your lifestyle? How does that compare to the average person? If everyone had the same lifestyle as you, how many earths would we need to survive? The second quiz gives results about the number of earths needed to sustain you, and a breakdown of what areas of your lifestyle are consuming the most natural resources.

The first quiz is provided by an organization called “The Global Footprint Network” and the second by “The Center for Sustainable Ecology.” Besides the quizzes you can also find a good bit of information on conservation at either website. The quizzes are definitely eye-opening and can lead to some great discussions about protecting the environment and conservation of natural resources.

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Water Conservation

Water Conservation

How many times do you have to remind your kids . . . “Turn off the water!” . . . or, “Turn off the light when you leave the room!” Kids are forgetful and they sometimes need help developing good conservation habits. Here’s a simple activity that will make your kids aware of how much water they can waste simply by brushing their teeth!

1. Find a large bowl that will just fit into the sink to collect water running from the faucet.

2. Have your child brush their teeth as they typically do, leaving the water running the entire time.

3. When they finish brushing and rinsing, measure the volume of the water collected in the bowl. You can use any measurement that works for the tools you have on hand. Cups might be the best, as you can convert your final measurements into gallons. Students have a good concept of how much a gallon is when they think about a gallon of milk.

4. Repeat the process, but this time, have your child turn off the water when they are not using it to wet the toothbrush, rinse, etc. When finished, measure the amount of water used.

5. Have your child subtract the difference between the amount of water used when running the faucet the entire time and when only turning it on when necessary. Convert to gallons: 1 gallon = 16 cups.

6. Finally, have your child calculate the number of times they brush their teeth in one year. Multiply by the amount of water that can be saved at each brushing. The amount of water wasted each year by letting the faucet run is surprising!

7. To extend for older children . . . multiply that amount of water by the number of people in your household to see how much water the family could save in one year. Then, help your child read a recent water bill to determine how much your utility company charges per gallon of water. Use that figure to calculate the amount of money your family could save by turning off the faucet while brushing your teeth!

Disclaimer: If you follow this project through to the very end, be ready for your child to transform into the “faucet police”! 🙂 Once children “see” the results of conservation techniques they do tend to become aware of what everyone around them is doing!

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