real science for today's homeschooler

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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Learning about Buoyancy in the Pool

Learning about Buoyancy in the Pool

Buoyancy seems like a simple concept, but to fully understand it on a scientific level can be a challenge for students. Introduce the concept to your younger elementary kids in a fun way while playing in the pool this summer!

Buoyancy is based on Archimedes’ Principle that states, “Any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object.” Very confusing language for kids! Here’s how to explain Archimedes in their language . . .

When you get in the pool, your body shoves some water out of the way to make room for you. Let’s say you could collect all the water your body moved out of the way and weigh it. Now, pretend that you lie down on the ground and have someone put all that water on top of you. You would feel the water pushing down on your body, right? That push you feel is a force. So, when you get in the swimming pool, the water you move out of the way starts pushing back. But instead of it pushing down on you, it pushes up trying to push you back out of the water. That force of the water trying to push you back out of the pool is called buoyancy!

Relate Archimedes’ Principle to what your child “feels” while in the pool. You feel lighter in water than you do out of the water because the water is actually pushing up on you . . . holding you up a bit!

If your child is able to understand the basics of Archimedes’ Principle, go a step further with the concept. If the weight of the water displaced is more than the weight of the object, the object will float. If the weight of the water displaced is less than the weight of the object, the object will sink. Ask them to explain why they sink in the water (when they don’t swim), but float when they lay on a float.

Finally, if your child swims well enough to “dive” for objects underwater, introduce a challenge. It’s them against the water! When they try to go underwater to get a object at the bottom of the pool, the water is trying to push them back up. The challenge? Who is stronger, you or the water? 🙂

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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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