real science for today's homeschooler

Cooking Up a Chemical Change

Cooking Up a Chemical Change

Chemical change can be a hard concept for children to understand. It’s much easier to explain a physical change. Water freezes into ice. The ice is still water and can be melted back into liquid water. Tear a piece of paper in half, and you still have the same paper. Both are physical changes. But how do you demonstrate chemical change?

The easiest example of a chemical change is burning a piece of paper. The paper turns to ask and becomes a new substance, much different from the original paper. But, what about other examples? Try baking! Spend some quality time with your child, make dessert, and teach science all at the same time!

A cake or cupcakes are probably the best desserts to use to clearly show a chemical change. Before getting started, collect all the ingredients that will go into the cake batter. You don’t have to make a “scratch” cake for this to work. Even if you’re only adding eggs, oil, and water to a cake mix, students can still observe the chemical changes.

Have your child observe all the beginning ingredients. Older children can make a written list of the physical properties (characteristics) of each of the ingredients. Do let them observe the ingredients directly . . . open the cake mix pouch, break the egg, etc.

Now, mix up the batter while letting your child help at a level appropriate for their age. While mixing ingredients, discuss changes that are taking place. Point out that even though they may look different, the ingredients are all still there and haven’t changed into anything else. For example, the egg is mixed in the batter, but it is still egg. Have your child observe the final raw batter. Point out that the batter is a “mixture” of ingredients, but none of them have been chemically changed.

Finally, add heat . . . bake the cake! Make observations of the ingredients after they have cooked together. Point out that one evidence of a chemical change is that you come out with a completely new substance that doesn’t look anything like the original. Going from cake batter to a fluffy cake will be a clear example of “forming a new substance” to your child. Also, ask your child what was needed to make the chemical change happen. Heat! Point out that many chemical changes require heat. The heat causes the original substances to recombine to form new substances. Who knew Chemistry could taste so good!

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Backyard Ecology

Backyard Ecology

No matter whether you live in the country or the city, your child can observe nature close to home. Help your child be a nature detective to discover the ecosystem existing right in their own backyard.

First, help your child identify what types of plants and animals they are realistically likely to see. If you have land in the country they’re likely to observe large mammals such as deer and racoons. If you have a tiny backyard in the city, help your child realize that they will be looking for small animals such as insects, lizards, birds, etc.

Depending on the age and interest of your child, prepare a plan to capture an image of the plants and animals they find. A digital camera works well, but if your child likes to draw they can turn the ecosystem hunt into an art project.

Over a span of a week or two, sit quietly outside with your child and observe nature. Have them find as many different plants and animals as possible. To find some of the more shy animals, help your child turn over rocks and other objects in the yard or on the porch. Try observing at different times of day, and even go outside with a flashlight at night to find animals that come out after dark.

For younger children you may just want to print out the photos and identify the different types of plants and animals found. They can make a collage or a notebook to display what’s living in their backyard. Older children may also want to research what each type of animal eats and design a food web based on that information. One method is to glue the images on a poster board. Then draw arrows going from the prey (or plant) to the predator. Older students can then examine their food web to infer other animals that might be a part of their backyard ecosystem that were never observed.

Whether you focus on the exploration or turn the project into an in depth ecology lesson, your child is sure to gain an appreciation for nature’s ability to sustain life anywhere!

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Outdoor Activity Explains Energy and Work

Outdoor Activity Explains Energy and Work

Energy is defined as the “ability to do work.” Energy and work are really different forms of the same thing, but to a child, they are very different. Try this simple outdoor summer activity to demonstrate the relationship between gravitational potential energy and work.

First, children need to understand gravitational potential energy. Explain to your child that a ball on the floor has no potential energy because it won’t move by itself. But, a ball on the edge of a shelf has potential energy because it can fall off of the shelf. While the ball is moving, it has energy. While the ball is sitting on the shelf it has “potential” energy because it has the “potential” to fall.

Children also need to know that the scientific definition of “work” is moving an object through a distance. The larger the object and the farther the object is moved, the more work is done on the object.

Next, explain to your child that energy is “the ability to do work.” Relate this to the ball sitting on the shelf. When the ball falls off the shelf and hits the ground, will it do work? (Technically, the answer is yes. The ball will transfer energy to the molecules in the floor, causing them to heat up slightly. But, this is not something that can be easily explained or understood by a child!) The following activity will help your child answer the question.

1. Place a pan of water on the sidewalk or driveway so water splashing out can be easily observed and/or measured.

2. Use a ball that has enough weight to make a splash when dropped into the pan of water. Raise the ball 1 foot above the surface of the water. Drop the ball into the water and observe.

3. Small children can observe how far the water splashes, or mark the farthest splash with sidewalk chalk. Older children should measure the distance from the edge of the pan to the farthest splash and record.

4. Fill the pan if needed. Repeat the ball drop from a height of 2 feet. Observe, mark, or record how far the water splashes from the pan.

5. Continue several more trials so that your child can observe that the higher the height of the ball, the farther the splash.

Now, relate the activity to the concepts of energy and work. When the ball is held above the water, the ball has potential energy. The higher the ball is held, the more potential energy it has. When the ball is dropped, the potential energy is released and the ball moves. (Technically, the potential energy is converted into kinetic energy, or the energy of motion. You may want to introduce this added concept with older children.) When the ball hits the water, the energy from the ball is transferred into the water, causing the water to splash out of the pan. Since the water is moved through a distance, the ball does work on the water. The more potential energy the ball started with, the more work it does on the water, and the farther the water can be moved.

To extend the activity and allow your child to use up some of their own potential energy, encourage them to experiment with “adding energy” to the ball by throwing it into the water to see how far they can get the water to splash!

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Periodic Table Basics

Periodic Table Basics

If your child has already learned about the parts of an atom (proton, neutron, and electron) they can understand the basics of the periodic table. From a basic periodic table, a young student can find: 1) the abbreviation for the element’s name, 2) how many protons an atom of the element has, 3) how many neutrons an average atom of the element has, 4) the number of electrons a neutral atom of the element has. Use the information below to teach your child the basics of using the periodic table. Then, turn the Periodic Table into a game. Give “clues” to a particular element and have your child use the clues to identify the element. You’ll find few examples of element clues at the end of this post to get you started.

Here’s an overview of periodic table basics:

periodic tableThe one or two letter symbol in each box is an abbreviation for the name of the element. In the example on the right, the abbreviation for carbon is C.

The number that is always above the symbol is the atomic number of the element. The atomic number gives the number of protons in one atom of that element.

The number under the symbol is the atomic mass. It is the average number of protons plus neutrons found in one atom of the element. You can use that number to find the number of neutrons in an average atom. Just subtract the number of protons from the rounded atomic number and you will have the average number of neutrons in one atom of the element.

Finally, in a neutral atom the number of electrons is always the same as the number of protons. So, the atomic number also gives the number of electrons in a neutral atom of the element.

Element clues:

1. Which element has 80 protons?

2. Which element has 16 neutrons and 16 electrons?

3. Which element’s name is abbreviated Fe?

Continue using the periodic table to make clues as long as the game holds the student’s interest. The more they become familiar with the periodic table now, the less intimidating it will be in upper level science classes!

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Make Waves in the Tub

Make Waves in the Tub

Light waves . . . sound waves . . . it’s all pretty hard for a younger elementary student to understand. They can see light and hear sound, but the wave part just isn’t something they can perceive with their senses. A good way to begin to introduce the topic of waves is with water waves. A wave that is visible and moves slowly enough for them to observe the actual wave itself.

Use bath time as a way to introduce the topic of waves to your younger child. Here are some basic wave properties that can be observed in the tub:

1. Have your child make a series of waves in the water and observe. The highest point in a wave is called the crest. The lowest point is the trough. As you make waves toward your child, have him/her point out or try to catch a crest and a trough.

2. The distance between the crest of one wave and the crest of the next wave is the wavelength. Have your child experiment to find a way to make waves with a long wavelength and then with a short wavelength. Talk about what determines the size of the wavelength. (How fast the child moves determines the wavelength. All waves are caused by vibrations. The speed of the vibration determines the wavelength.)

3. The distance between the height of the crest and the midpoint of the wave (the water level if there were no wave) is the amplitude. Have your child experiment to find a way to change the amplitude of the waves. Talk about what determines the size of the amplitude. (Amplitude is actually determined by the amount of energy in the wave. The more energy your child puts into making a wave, the larger its amplitude will be.)

Through this bath time activity, your younger child will learn the basic parts of a wave and two fundamental wave properties. And, they will be a little cleaner, too! 🙂

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Understanding and Measuring Friction

Understanding and Measuring Friction

For elementary children, the topic of “opposing forces” can be hard to understand. Friction is an opposing force that children can “feel.” Here’s a lab on measuring and comparing friction that’s appropriate for older elementary children. You will need one piece of “science equipment” to get the most out of the lab . . . a spring scale. A spring scale with small increments will be easier for elementary children to use.

Here’s what to do:

1. Find an object that can be easily hooked onto the spring scale, that is fairly heavy (but will still read when hung from the spring scale), and preferably with a large, flat surface. A heavy block of wood with a cup hook works very well.

2. Have your child hook the object onto the spring scale and drag it across the smoothest possible surface you can find. While dragging the object slowly, have your child read and record the amount of force they are using to move the object. (Newtons is a measure of force, so the part of the scale marked as “N” is actually a measure of force.)

3. Next, have your child hunt for 5 different surface with as many different textures as possible. The surfaces must be large enough to drag the object across, just as was done in step 2.

4. Ask the child to predict what will happen when they drag the object across the different textured surfaces. They will most likely come to the conclusion that some surfaces will be harder to pull across than others. Ask them to come up with an explanation for WHY this is true.

5. Introduce the topic of “friction” by explaining that friction is a force that acts in the opposite direction from the force you apply to move an object. When they drag their object one way, the surface tries to pull it the opposite way!

6. Now, have your child predict which of their selected surfaces will pull more than others. Have them rang the surfaces in order from least friction to more friction.

7. Finally, it’s time to test their predictions. Have your child drag the object in the same way across each of the different surfaces. As they are slowly dragging the object, they should read and record the force they must use to pull the object.

8. Subtract the force needed to pull the object on the smooth surface from the force needed to pull it on each of the textured surfaces. This is a measure of how much more force the textured surface was putting on the object. The larger the number, the more friction force was applied by the surface.

To put it all together, remind your child that a force is just a push or a pull. So, when they put a force on the object in one direction, the surface will put a force on the object in the opposite direction. The more force applied by the surface, the harder they have to pull to get the object to move.

As an extension, relate this topic to the practical chore of moving a heavy object. Have them brainstorm ways that can be used to make sliding a heavy object easier.

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Calculate Speed While Encouraging Exercise

Calculate Speed While Encouraging Exercise

We all know that kids have a lot of energy. Put that energy to good use by combining a physics lesson, a math lesson, and some good exercise! All you’ll need is an energetic kid, a tape measure, a stopwatch, and a safe place for your child to run.

Calculating Speed

1. Pick out a “track” that your child can run safely. Select a distance appropriate for your child to run several times.

2. Help your child measure the distance of the selected track with the tape measure. You can measure with any units: yards, feet, meters, etc. Have your child record the track distance.

3. Measure the time it takes for your child to run the selected track. If possible, measure the time in seconds. Record.

4. Introduce the formula used to calculate speed:  speed = distance / time

Depending on the math level of your child, help them calculate their speed by dividing the distance of the track by the time it took to run it. Older children can calculate speed using long division. For younger children you may want to introduce the usefulness of technology by showing them how to get their answer with a calculator.

5. Repeat the run with the same track, or a different one as long as your child is interested and energetic. Challenge them to improve their speed with each run.

As an extension of the lab, students can compare their speeds when a) wearing different types of shoes, b) running on different surfaces, or c) running courses of different lengths. Any of these options will increase your child’s interest in the lab, as well as give them extra practice with division . . . and a little more exercise!

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Cotton Cloud Model

Cotton Cloud Model

If you’re teaching your kids about the different types of clouds, have them make a model to show cloud structure and the different levels of the atmosphere where clouds form. Here’s a good website that covers the basics of cloud classification. There’s a good diagram of different types of clouds and the atmospheric levels in which they form. For younger children you might want to let them use the image as a guide for their model. Older children will find it more challenging to only research information about the structure and level of different types of clouds and then develop their own visual model.

Whichever option you choose, provide blue foam board, plenty of cotton balls, school glue, and markers. Challenge your child to plan their model before beginning. Discuss the need to arrange the cotton so that it represents the structure of different types of clouds. And, the need to plan ahead to divide the poster into sections to represent the different levels at which clouds form. A black marker can be used to darken the cotton of the “rain clouds.”

Extend the cloud lesson by taking the finished model outside on different days to identify clouds in the sky. The model will help children understand that they are actually looking up through three different levels of clouds.

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Bug Collection – Go Digital!

Bug Collection - Go Digital!

Remember having to do a “bug collection” project when you were in school? There is a lot of value in observing animals in their natural environment and learning how to identify them based on physical characteristics. But, is it really necessary to catch, kill, and mount them?

If your kids are afraid of crawly things or squeamish about killing live creatures, why not have them do a “virtual bug collection”? Armed with a digital camera, kids can hunt for insects in their natural environment. Teach them how to approach the insect slowly and quietly so they can get a close up snapshot. These pictures can then be used to study the physical characteristics to identify common names or even scientific names for older students.

You can either print out the digital photos and preserve their virtual insect collection in a notebook, or help them make a PowerPoint from their collection to incorporate a lesson in technology!

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Red Cabbage as a pH Indicator

Red Cabbage as a pH Indicator

pH is a hard concept for younger children to learn. Add a little excitement to the subject of acids and bases by using a natural pH indicator. First, the science . . . an indicator is a chemical that “indicates” or shows the presence of a substance, usually by a color change. There are many pH indicators, each working for a different range on the pH scale. A wide-range indicator detects substances on the entire pH spectrum.

A safe and easy pH indicator for kids to work with is cabbage juice. When added to different household substances, it turns a wide range of colors, which children love! Here’s how to prepare the indicator: Pinch up the very red (purple) leaves of a red leaf cabbage. Put in water and boil until the reddish purple color comes out into the water. You can do this on the stove, but the microwave works well, also. A few hints . . . use a high cabbage to water ratio as you want the color as concentrated as possible. And, use soft water. If your water is naturally soft, tap water will work fine. But, if you live in an area with hard water, it’s worth the cost to buy some distilled water for this activity. Cool the cabbage juice before using. It will store for several weeks in the refrigerator.

Next, have your child collect different household liquids they want to test for pH. You can find a list of the pH of some common liquids here. You can also just search “pH of ???” on the internet to find the pH of just about anything. Testing liquids from a wide range on the pH scale will give the most colorful results.

Once you have all your test liquids, add about a tablespoon of each to a test tube. (If you don’t have test tubes at home, the cups of a white egg carton work great!) Then, add a teaspoon or so of the cabbage juice indicator to each test liquid. The amount isn’t critical. Just add enough cabbage juice to get a good color change.

For older children, make a list of the test solutions and their actual pH collected from the internet. Have your child create a color scale that can be used to determine the pH of an unknown substance. For example, here’s a pH scale for another commercial indicator:pH scale

Once your child has made a pH chart for cabbage juice indicator, provide him/her with several “unknowns” to test the accuracy of their chart.

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