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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Fingerprints

Fingerprints

A fun way to teach kids about their skin is through an activity on fingerprints. The skin has two layers: the dermis and the epidermis. The epidermis is the layer of dead cells on the outside of the body that waterproofs and protects the living tissues underneath. The dermis is the living skin layer that contains blood vessels, sensory receptors, and the dividing cells that create the epidermal layer. The upper part of the dermis has finger-like projections that stick up into the bottom of the epidermis. These projections, called papillae, allow the sensory receptors to be closer to the surface of the skin. In some areas of the body (palm side of hands and fingers, and bottom of feet and toes) the papillary layer is much thicker, causing it to bunch up between the epidermis and the lower dermis layers. This bunching causes the ridges and valleys we call fingerprints.

Contrary to what most people think, identical twins do not have identical fingerprints. Although genetics does determine the basic pattern, conditions in the womb influence how that pattern actually develops. Factors like rate of bone growth, pressure in the womb, and contact with amniotic fluid all affect the development of fingerprints of the fetus. Since it is virtually impossible for all those conditions to be exactly alike for 9 months, it’s safe to say that no two people have exactly the same fingerprints. The tiny details, called minutiae, that are used by forensic scientists to analyze fingerprints found at a crime scene are slightly different for everyone.

But, there are some basic fingerprint patterns and your child can easily recognize. Here are the basic fingerprint patterns:
fingerprint patternsLet your child make prints of his/her own fingerprints and identify the basic type. To make really detailed, long-lasting prints, use an ink pad. The ink will stay on the fingers for a few days, but most can be removed with rubbing alcohol and a good hand-washing. For a less permanent way to make prints, rub pencil “lead” heavily on one spot on a sheet of paper. Have your child press their finger firmly into the mark and then transfer over to clean paper to make a print.

Extensions of the basic fingerprint identification:

1. Fingerprint other members of the family and compare and contrast the prints. Do you find similar patterns? Different patterns?

2. For older children, use a magnifying glass to examine prints for tiny details (minutiae). Examine two fingerprints with the same basic pattern and see how many differences you can find. Examining prints at this level provides practice with observation skills and attention to details.

3. Set up a “who done it” activity for your child. Fingerprint several “suspects” and then make one “crime scene” fingerprint. Label all the prints with the suspects name or “crime scene.” Your child will have fun matching the crime scene print to one of the suspects! Adjust the difficulty level to the age of the child. For older children, choose a crime scene print that looks similar to the fingerprints of multiple suspects. Provide a magnifying glass so they can find a match by examining the minutiae of each print.

 

 

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Invisible Ink as a Chemical Reaction

Invisible Ink as a Chemical Reaction

Kids love spy gadgets and mystery! Use homemade invisible ink to write secret notes, then teach your child the science behind the process used to reveal the hidden messages.

There are many ways to make invisible ink. To use one of the safest methods, just use a Q-tip to write or draw on white paper with lemon juice. Actually, any fruit juice that contains citric acid will work, but lemon juice tends to dry the clearest, keeping the message hidden until revealed.

To reveal the message, the paper needs to be heated in some way. Whether or not your child can do this by themselves depends on the age of the child and the method used. Below are several ways to made the message visible. Choose the one most appropriate for your child:
1. Hold the paper over a candle. This is a slow method, requiring patience, as the candle can easily scorch the paper if brought too close.
2. Hold the paper over a hot light bulb. This method is very similar to the candle, but it does heat a larger area. The bulb must get very hot. For example, a 100 W incandescent bulb. Fluorescent bulbs won’t work. Care should be taken not to touch the bulb!
3. Carefully iron over the paper. Gives you a quick reveal but for safety, this needs to be done under direct parent supervision.
4. Heat the paper for about 5 minutes in the oven (around 350 degrees). Watch carefully to make sure the paper doesn’t overheat and burn. Again, direct parent supervision is needed for this method.
5. Hold the paper over a toaster. The hot air rising from the toaster should be enough to reveal the message.
6. Direct sunlight on a very hot day will sometimes be enough heat to bring out the hidden message.
7. I have heard that a very hot blow dryer will reveal the message, but I’ve never had any luck with this method.

Here’s the science behind the reveal . . . Paper is made of cellulose, a starch that makes up the body of plants. Cellulose is a tough, fibrous molecule made of many, many glucose (sugar) molecules connected in long chains. The acid in the lemon juice naturally breaks down the cellulose, separating the individual glucose molecules, which is a chemical reaction. Heat makes that process work even faster, as raising the temperature almost always increases the rate of a chemical reaction. The heat also caramelizes the sugars now in the paper, turning them a brown color. So, the brown message you see on the paper is actually caramel!

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Dinosaur Tracks

Dinosaur Tracks

Scientists often have to use indirect evidence to infer information about extinct species. Children (and adults!) often find it hard to understand how a footprint can tell a scientist anything about the animal that made it. Use this “mystery solving” activity to help explain how information can be collected from indirect evidence.

You will need to do a little advance preparation for this activity. You’ll need some play dough or other soft modeling clay and some plastic dinosaurs. Dinosaur models of different sizes and different types of dinosaurs will work best.

  1. Roll out the modeling clay in a flat sheet. This represents an area of soft mud like you would find along a river bank.
  2. Use the plastic dinosaurs to make footprints in the clay as if the dinosaur were walking through the mud. Be sure to space the footprints out to represent the natural stride length of the plastic figure. Also, adjust the depth of the footprint to represent the relative size of the dinosaur. A larger dinosaur would weigh more and so would sink farther into the mud, etc.
  3. Adjust the complexity of the footprint pattern based on the age of your child. Keep the pattern simple for younger children with only a few different dinosaurs with tracks spread apart. For older children, add more dinosaurs and have one track cross over another, etc.
  4. Allow the clay to dry completely. Don’t let your child see the clay or the dinosaur figures until you’re ready to have them do the activity.

The activity:

  1. First, give your child only the clay model. Explain to your child that this was once soft “mud” that dinosaurs walked through. Over time, the mud dried up and turned to “rock.” The footprints are indirect evidence that a dinosaur walked through a long time ago. If your child is old enough you can introduce the term, trace fossil. A trace fossil is anything that shows a prehistoric organism was there, but it doesn’t show what the organism actually looked like.
  2. Ask your child to look at the field and identify how many different dinosaurs walked through the field. For older children, have them trace the path of each different dinosaur, explaining what happened when paths crossed, etc.
  3. Now, have your child look at each different track present. Ask them to tell as much as they can about each dinosaur based on their footprints. Allow your child time to develop ideas on their own. Here are some things to suggest if they get stuck:
    • Ask children to compare foot size between members of their own family. Lead them to recognize that larger people have bigger feet and apply that to the dinosaur tracks. Have your child put the dinosaurs in order based on relative size.
    • Did each dinosaur walk on two legs or four legs?
    • Discuss “stride length” as it relates to height. Your child has probably noticed that they have to take more steps to keep up with dad! Explain that taller people usually have longer strides. Have your child relate this idea to the dinosaur tracks. Can they tell which dinosaur was taller and shorter based on stride length?
    • Have them measure the depth of the track. Relate this to the weight (size) of the dinosaur, since heavier objects would sink farther into the wet mud.
    • Finally, if any of your dinosaur figures had distinctive features on the feet, see if students can identify these from the footprints. (This all depends on the models you use. For example, some models may be detailed enough to show individual toes, claws, etc.)
  4. After your child has inferred all they can from the footprints, bring out the models that were used to make the prints. Have your child match up the dinosaur to their footprint. Compare all the figures used and evaluate how accurate your child’s predictions were to the real thing.

To extend the lesson, do an internet search to see of there are any dinosaur tracks close enough for a local field trip or a stop along your next vacation route!

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Teaching Kids about Consumerism and Conservation

Teaching Kids about Consumerism and Conservation

Let’s face it, the advertising world targets your kids every day. What child hasn’t been disappointed after saving for months for a toy, only to find it doesn’t measure up to what the commercial promised? In my science classes I teach my students how science can be used to objectively test claims made by advertisers . . . in other words, how to be wise consumers. Here’s a fun idea that actually came from one of my students. It combines a lesson about consumerism, along with a lesson about conservation.

Design an experiment to test which is more cost efficient, using disposable or rechargeable batteries. I’ll list some of the variables to consider below, but your child can easily design this experiment themselves for some hands on practice using the scientific method.

1. Pick comparable battery brands to test. If you pick a name brand disposable battery, don’t compare it to a cheap store brand rechargeable, etc.
2. Use the same size battery of each type.
3. Test the battery life in the same way. An example would be using the battery to run any small electronic device. Measure the time the device remains in operation. Use the same device for both types of batteries, and keep the device under the same conditions (temperature, volume, etc.)
4. Decide on exactly what you’re comparing. Are you comparing the amount of time each battery will keep the device running? If so, you may want to also test different brands of each type. Are you trying to determine which type (disposable vs rechargeable) battery costs less in the long run? In that case, you’ll need to also factor in how many times the rechargeable can be recharged vs how many disposable batteries would have to be purchased to get the same result.

Again, those are just some suggestions of things to consider when designing the experiment. Your child will have plenty of ideas of their own. Gently guide them into using the scientific method to design their experiment so their results are valid.

Extensions of this lab are limitless! Older students can research the amount of waste produced by batteries or the amount of nonrenewable resources are used in the manufacturing of batteries. Find battery commercials or ads for the different brands and types tested. Challenge students to evaluate the claims made by the manufacturers based on the results of their experiment. This will usually lead to a discussion about the accuracy of claims made about other products. Encourage your child to select several products that are commonly used in your home and put them to the test! Teaching kids not to believe everything they see and hear from the media, and teaching them that they have the power to evaluate these claims for themselves is a valuable life lesson!

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Inexpensive microscope substitute

Inexpensive microscope substitute

One of the most expensive pieces of science equipment to purchase for home studies is a microscope. A good microscope is really a necessity for middle and high school studies, but there’s a cheaper alternative for the earlier grades. You can purchase an “illuminated pocket microscope” for anywhere from $10-$30, depending on the light source and magnification level. It’s definitely limited in what it will do, and it’s no substitute for a real microscope at the secondary level. But, for elementary studies, it will magnify objects well enough for children to see details they can’t see with a regular magnifying glass.

A quick internet search for “illuminated pocket microscope” will give you many sources from which to purchase one. Amazon has a wide selection. I haven’t found that any one brand works better than another. Just make sure it has a light source, and choose the magnification level based on how much you want to spend.

Be aware that the object being viewed must be held close to the pocket microscope, children must be able to look through a small eyepiece with one eye, and it isn’t made for viewing traditional slides. The light will shine on the surface of the object being viewed, not through it like a compound light microscope. You can check out a few different types being demonstrated by watching this utube video.

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Seed Germination Lab

Seed Germination Lab

Children are fascinated by the fact that a seed can grow into a plant. You’ve probably already planted seeds with your child in order to watch them grow into plants. Here’s a slightly different way to show your child the actual process of germination that allows them to actually see the plant emerge from the seed.

Materials: seeds, paper towel, plastic sandwich bag, magnifying glass

Procedure:

1. Fold a paper towel so that it fits flat inside a plastic sandwich bag.

2. Soak the paper towel thoroughly with water. You want the towel very wet from end to end, but not dripping with excess water. Place the paper towel in the bag and lay flat.

3. Place seeds on the paper towel so that they are spaced out away from each other. Press each firmly into the wet paper towel. (Hint: Although any type of seed will work, small, fast-germinating seeds work best. Whole birdseed such as millet works very well.)

4. Seal the baggie to conserve water and place the bag in a place where it will be undisturbed.

5. Gently slide the paper towel out of the baggie each day and observe the seeds with a magnifying glass. Depending on the type of seed used, you should start to see the seeds germinate within a few days to a week.

6. Between daily viewings be sure to gently replace the paper towel into the baggie and reseal. Re-wet the paper towel if it begins to dry out. You should be able to germinate the plants long enough to see the first leaves develop.

Lab Variations:

  • When the seedlings begin to produce leaves, transfer to soil and continue to grow into a larger plant.
  • Prepare more than one baggie with the same type of seed. Place the baggies in different environments (temperature, sunlight, etc.) to see how environmental factors affect seed germination.
  • Prepare more than one baggie with the same type of seed. Put differing amounts of water into each baggie to see how different amounts of available water affect seed germination.
  • Prepare more than one baggie using a different type of seed in each. Compare germination times of different types of seeds.
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