real science for today's homeschooler

Cloud in a Glass

Cloud in a Glass

As you’re studying weather, take a few minutes to make a cloud in a glass to help explain the process of condensation and cloud formation.

What you’ll need: clear glass or jar, kitchen matches, ice cubes, small plate or pan that will completely cover top of glass or jar (metal works best), boiling or very hot water

Procedure:
1. Fill the plate or pan with ice cubes and have it ready to quickly place over the top of the glass when needed.
2. Pour enough boiling water into the glass or jar so that there is about 1/2 centimeter of water covering the bottom.
3. Light a kitchen match and hold it inside the top of the glass for a minute or so. Right before the flame reaches your fingers, drop the match into the water in the glass.
4. Immediately, cover the top of the glass with the pan containing ice cubes.
5. Watch a “cloud” form inside the glass!

What’s Going On?
The boiling water has enough heat energy to cause some of the water molecules to evaporate and turn into water vapor inside the glass. Those individual water molecules will stay in a gas state as long as they have enough energy. When the pan of ice is placed over the top of the glass, heat energy from the water vapor molecules is transferred to the bottom of the cold pan. The water vapor molecules no longer have enough energy to remain in a gas state, and they condense back to a liquid state. The smoke from the burning match is made of tiny particles which remain suspended in the air inside the glass. As the water molecules began to condense, they collect around the smoke particles, forming the tiny water droplets that make the “cloud” in the glass.

How do Real Clouds Form?
Clouds in Earth’s atmosphere form in pretty much the same way. As the Sun’s energy heats water on the surface of the Earth, it evaporates. As the moist air continues to heat up, it begins to rise higher into the atmosphere. Earth’s atmosphere gets colder and colder the higher up you go. When the water vapor in the rising air gets cold enough, it condenses around “condensation nuclei” in the atmosphere. Condensation nuclei are tiny particles of dust, salt, and other solids that are suspended in the air, similar to the smoke from the match. When enough tiny water droplets form in the atmosphere, we see a cloud in the sky!

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Don’t Miss the Supermoon!

Don't Miss the Supermoon!

On November 14-15, 2016 we’ll experience a “Super Moon.” A full moon that is bigger and brighter than usual because the moon will actually be about 400,000 kilometers closer to Earth than normal. The last Super Moon occurred in 1948 and you’ll have to wait until 2034 for the next one. So, take your children outside tonight so they can experience their first Super Moon! For more information about the phenomenon, go here.

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Roadcuts – Windows to the Past

Roadcuts - Windows to the Past

The next time you’re traveling with the kids and need to stop for a break, look for a roadcut with a large safe shoulder to walk around. Call attention to the rock layers visible on the surface of the cut, and ask children for their ideas about what caused the layers. Depending on the age of the child, topics of discussion can include:

 

  1. the type of rocks and how they formed (most formed as sediments deposited as they settled out of water)
  2. fossils that may be found in the rocks (type of organisms give further hints about the conditions under which the rocks formed)
  3. the angle of the rock layers (sediment laid down underwater would form horizontal rock layers; if there are angled rock layers, how did they get that way?)

Help children understand that the farther below the surface, the older the rock layer. An analogy about building a brick wall may help younger children understand . . . the bricks at the bottom of the wall were put down first and the bricks at the top where added last. If fossils are present in the rock layers, talk about which of the organisms are older than others.

When you’re back on the road, encourage children to use their imaginations to draw what the area might have looked like when the rock layers were forming. If you found fossils, have them draw what the living organism might have looked like based on the fossil remains.

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How do you rate in general Scientific Knowledge?

How do you rate in general Scientific Knowledge?

Here’s an interesting Science Quiz done by the Pew Research Center. It contains some basic science knowledge questions in multiple choice format. Take the quiz and then see how you score against average American adults. You can also find overall results based on demographics. Follow another link to check out the full analysis of the poll that was designed to discover, “What the Public Does and Does Not Know About Science.”

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Earthquake Waves

Earthquake Waves

The general properties of waves can be investigated through an activity on earthquakes. First, have your child research the three different types of earthquake waves. Encourage them to find the following information about each wave:

1. name of the wave

2. how quickly it travels compared to the other two

3. what part of the Earth does it travel through

4. type of wave, based on motion (compression wave, transverse wave, etc.)

5. does it cause damage to buildings

Help your child organize the information they find into a chart or data table. This can be done on the computer or by hand. Or, make a poster and add pictures and drawings. Use the chart to compare and contrast the three types of earthquake waves.

Next, have your child build a structure that will withstand the different types of earthquake waves. (Encourage them to look at the type of motion caused by each wave.) Use any type of materials such as building blocks, boxes, DVD cases, etc. In order to test their construction, have them build it on a surface that will be easy to move, such as a small table, board, etc.

Test the structure(s) by recreating the various motions of the different earthquake waves:

P waves – move the surface back and forth in a horizontal motion

S waves – move the surface up and down

L waves – move the surface in all different directions, including circular motion

Older children may then want to research how scientists are designing earthquake resistant buildings.

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Take the Pluto Survey!

Take the Pluto Survey!

We all remember learning the nine planets of the solar system when we were in school. And just like that, there were only eight! Poor Pluto! In 2006 the IAU (International Astronomical Union) demoted Pluto to nothing more than a “dwarf planet” when another rocky body, similar to Pluto, was discovered beyond Neptune.

But, on September 18 Harvard University hosted a debate about the controversial classification of Pluto and it seems quite a case was made to reinstate Pluto back to its former planet status. Although you may have heard rumors that Pluto is now a planet again, the debate was informal and no official decision has been made. The IAU meets again in Honolulu, Hawaii in August, 2015 and no official change will be made before then, at the earliest. Still, the Harvard debate has stirred up quite a bit of emotions concerning Pluto!

I was very surprised to find that my students have very strong opinions concerning the fate of Pluto, with some believing it should be reinstated as the ninth planet of our solar system and some not. Which got me thinking . . . what a great topic to get kids involved in current events in science! So, I want to challenge you to get your kids involved. Encourage them to do some research on the pros and cons of classifying Pluto as a planet and come to their own decision. Once they have, please have them share their opinion through this one question survey. I’ll share the results of the survey when it looks like a clear winner has emerged! (The survey is completely anonymous and no information is collected other than the answer to the one survey question!)

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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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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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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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Growing Crystals with Common Chemicals

Growing Crystals with Common Chemicals

Crystal growing is a fun activity for kids and it is relevant to several areas of science, such as chemistry, as well as mineral formation in geology. Schools often use commercial chemicals to grow crystals in the classroom, and these chemicals can be difficult, if not impossible, to purchase as an individual. Here are a few household chemicals that can be used to grow crystals at home:

Aluminum potassium sulfate (alum) can be purchased in the spices area of the grocery store. This alum is not pure, and crystals do sometimes turn out small. Purchasing a more expensive brand will often grow better crystals, but alum is fairly expensive.

Sodium borate (borax) can be purchased in the laundry section of many stores.

Calcium chloride can be purchased at home improvement stores and stores that sell chemicals for swimming pools. Even at a specialty store, this is a fairly inexpensive chemical to purchase.

Copper sulfate is the ingredient in products used to kill roots in sewer lines. You can find this at home improvement stores. Moderately expensive, but a container goes a long way. This chemical makes very large, beautiful blue crystals and is a favorite for crystal growing. But, do be careful with storage of the crystals as the chemical is poisonous and it can be mistaken for candy by young children!

Magnesium sulfate (epsom salts) can be purchased at a drug store or the pharmacy section of the grocery store. It’s fairly inexpensive.

Sodium chloride (table salt) grows very nice cubic crystals.

Sucrose (table sugar) is used to make “rock candy” crystals. There are quite a few recipes on the internet for making rock candy, and it is a favorite to make. However, these are the hardest crystals to grow, and it can be messy! I’ve tried this using several different methods and have never been very successful. If anyone has a good recipe and growing technique for making rock candy, please post! 🙂

How to grow crystals:

The trick is to make a supersaturated solution of the chemical. It’s best to start with distilled water, which can be purchased by the gallon at the grocery. Heat the water, slowly add the chemical, and stir until completely dissolved. In order to make a supersaturated solution, the water needs to be very hot and you have to dissolve as much of the chemical as possible. Continue to add the chemical a little at a time, dissolving thoroughly before adding more. When you finally reach the point where no more chemical will dissolve, pour the hot solution into the container you’ll use to grow the crystals. You can also add a little food coloring if you want to make colored crystals. Don’t add too much as you don’t want to dilute the solution.

It’s important to use a container with very smooth inside surfaces, like glass. Also, be sure to only pour in the solution that is completely dissolved. Let the undissolved chemicals settle to the bottom of the original container and don’t transfer the last bit of solution. Finally, suspend a string into the crystal growing solution to give your crystals something to grow around, and leave undisturbed. Depending on the chemical used, crystals usually begin to form within hours, but may take several days to grow larger.

Safety:

Take care with the finished crystals and store them appropriately. Copper sulfate crystals are especially poisonous if ingested. Whatever chemical you use, do read the product label for safety precautions. The same precautions should be taken with the finished crystals! Remember, many candies are made to look like crystals and small children may not be able to tell the difference.

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