Monday, August 1, 2011

Experiments in Flight: Lift, Thrust and Drag

Sunflowers and pollinators (Kim Bennett (c) 2010)
I LOVE summer weather!. Our recent hot spell was a little TOO summery for most members of this family, however. Most of our outdoor activities were limited to the early morning or after dinner hours, unless we were (all!) in the kiddy pool!

Here in Connecticut, our weather broke a lot of records, topping off the week with one day where it reached 103 degrees at Bradley Airport.

Kim Bennett (c) 2010

A side benefit of all that heat is that the vegetable garden has gone bananas! The snap peas, onions and most of the potatoes finished up, and the tomatoes grew like they were jungle vines. Malik ate most of the peas before they got to the house. The cherry tomatoes didn't make it to the house after I picked them, either (they are so delicious!) -- can't wait for the big ones to ripen!  Eggplants are on the way, too, as are the first of the hot peppers (a special request from my husband, this year)...

Bee balm attracts hummingbirds (Kim Bennett (c) 2010)
The warm weather did bring the ruby-throated hummingbird to our yard. We can't quite catch him on film, but he's been seen frequenting the bee balm, so we put out the hummingbird feeder in hopes of getting him to sit still for a photo.What a lot of noise from a tiny, little bird!

Here is a great video clip (not mine) of some RTHs having a conversation at the feeder.

We are continuing the bird study from our June newsletter, by studying the blue jay and its cousin, the crow (see Outdoor Hour Challenge #2, Jays and Bluebirds). We have also begun our Zoology unit with a study on wings and flight, from Apologia Science (Zoology I: Flying Creatures of the Fifth Day). [I am a science teacher, by training, and I absolutely love the Apologia text books, as does my son -- high quality, very deep in science content, and full of hand-on activities.] As part of our first week of lessons, we conducted an experiment to study the effects of wing size and shape on gliding distance.

First, we read our chapter on drag, thrust and lift, and learned about the special shape of a bird wing (called an airfoil), and why the shape of a bird's wing (or a plane's wing, modeled after a bird's wing) allows a heavier than air object (like a bird) to seemingly float above the air. [Boeing has a great page on "How Do Things Fly?" which is a great, kid-friendly reference on wings and flight.]  Then we completed a Scientific Experiment Planning Sheet, which followed the scientific method, and listed our materials and procedures. While we completed it, we decided which was our independent variable (wing shape) and which was our dependent variable (gliding distance). We formulated a hypothesis that wings that were long and narrow would allow the glider to glide farther than wings that were short and wide.

Our flight experiment (Kim Bennett (c) 2011)
Next, we designed two simple gliders from common household objects. These gliders were identical in every way, except for the shape of their wings (we learned that we had to make sure that ONLY our independent variable varied, or we couldn't come to a conclusion about our hypothesis).

We used an old cereal box to create the wings and tail fins, drinking straws, and two identical blobs of homemade playdough for nose weight. We taped the wings to the straw using adhesive tape.  The only difference between the two planes was the shape of the wings.

Ready, fire! (Kim Bennett (c) 2011)
Then, we needed to find a good place to launch our gliders. We knew that gliders depend on height for distance, so Malik suggested that we climb to the back porch on the second floor. You can see our gazebo and hedges in the back yard.

It was important that we launched our gliders many times, to account for strange things that might happen (such as one of the cats chasing one of the gliders, a glider getting caught in the hedge, the blob of playdough falling off a nose piece, and other things that really happened). It was also important that the gliders were both thrown the same way, each time, so Malik was in charge of launching, and Mom was in charge of fetching (it was like being on a two-story Stair Master...).  We had a tape measure, but decided to pace off the flight path of each throw, using Mom's feet as a non-standard measuring tool. Mom called out distances, and Malik recorded on his data sheet.

Data tables (Kim Bennett (c) 2011)
After we had thrown the gliders ten times, each, we calculated an average distance for each glider. We accepted our alternative hypothesis that long, narrow wings let an object glide farther (the null hypothesis would be that wing shape had no effect on gliding distance).

We lost one nose piece on the last glide, but the wings were good for another go-around on another day. How might we change our experiment to learn more about lift, thrust and drag?

Notes from the science teacher:
  1. Conducting a simple experiment is powerful science, for all ages! Even small children can be taught to follow up a question ("Mommy, what will happen if I mix red and blue paint?") with, "How can I find out?" and "What do I think will happen?" 
  2. Little kids can use pictures to draw what they think will happen, and what actually happened. As children get to be 1st and 2nd graders, tally marks can be used to take count data. Third graders and older should learn how to create a simple data table (see the photo, above, for our non-fancy, two-column data table).
  3. Introduce the steps and words of the scientific method early on: hypothesis, materials, procedures, data, analysis, conclusion, dependent and independent variable. Don't teach substitute words if the real ones will do!
  4. Always tie the experiment back to the concept you are teaching. So many high school students remember the experiment where they burned something, blew something up, or added water, but they don't remember what the experiment taught them!

    For more information on conducting experiments with children, see the following resources:

    How to Conduct Science Experiments
    Kids' Science Experiments
    Fun Science Experiments for Preschoolers

    For more experiments on flight, see these links:

    Paper Helicopters and  the Methods of Science
    Paper Airplane Experiment for Kids

    There is also a Web Quest on flight which you might enjoy.

    We live minutes from the New England Air Museum, which will be our next field trip (after successful completion of our bird study and flight lessons). We'll post photos!

    We had a lot of fun together. It was educational, outdoors and exercised our bodies!

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