Friday, August 30, 2013

Over in a River...

Over in a River: 
     Flowing Out to the Sea
by Marianne Berkes; illus by Jill Dubin
32 pages; ages 3-8
Dawn Publications, 2013

When my youngest son was about 6, he wanted to know where the little stream that runs near our house started. And where did it go? And did otters live in it somewhere? So we pulled on our boots and hiked upstream, following the ever-narrowing trickle across rocky places and through marshy places until we found the spring where the stream was born.

Then we got in a car and followed it down our hill, where it joined another stream, and further, where it joined a creek, and further yet, to where it joined the Susquehanna River.We never found any otters - but I hear that there are some in the river.

So I was excited to see Marianne Berkes' newest book that features rivers - and the awesome cut-paper artwork of Jill Dubin. This is a counting book, and you can sing along with the text... but there's a lot more to it. Each page introduces an important river ecosystem and the animals that live there. You'll meet herons and salmon, manatees and - yes! - otters. You'll learn a little geography as you go along, plus there's some hidden animals in the pages. And, for those kids who love to explore nature through art, Dubin gives some tips on how to create your own cut-paper art.

Check out more science and nature resources at STEM Friday.

Review copy provided by publisher.

Friday, August 23, 2013

Flight Plans - make a helicopter

One of the fun things I do as a volunteer at Ithaca's Sciencenter is build helicopters with kids - and parents, grandparents, teachers.... everyone loves to make 'em. So I thought to go along with my review of Explore Flight! over at STEM Friday, that I'd share some helicopter flying here.

According to historians, kids have been playing with helicopter toys for the past 2500 years. All you need is a blade attached to a stem; give it a good rub and set it spinning. In the 1480s, Leonardo daVinci created a design for an "aerial screw" - and in 1906 French inventor Paul Cornu built a machine with 20-foot rotors powered by a small engine. It lifted him a foot off the ground and kept him there for 20 seconds.

Our helicopters won't have engines; they're more "helicopter-gliders". The spinning blades provide enough lift to slow its descent. And since it's a vertical flier, it only goes one direction: down.

Start with a template - this is the one we use for the kids and you can find a downloadable version from the Chicago Museum of Science and Industry. You'll need a few items:
  • scissors
  • ruler
  • paper
  • paperclips
  • pencil
Cut along solid lines. Then fold sections A & B along the dotted lines, and fold up the bottom to keep the "stem" from unfolding when you fly. Bend the blades (D & E) with one folded towards you and one away. Then try flying your 'copter. Hm-m-m... I wonder if a paper clip might help it fly better?

When you drop your helicopter, it pushes the air that's around it out of its way. The air pushes the blades into a slanted position (drop it again and watch closely). According to the folks at the Exploratorium,  the air under one blade pushes one way and the air under the other blade pushes the opposite direction. Those two forces push the blade around and make it spin.

So what happens if you angle the blades? Put a bend in them?
What happens if you make a 'copter with blades that are twice as long? Or twice as wide?
What if you cut jagged edges on the blades or make them rounded?
 What if you have one blade fatter or longer than the other?
What if you make 3 blades? or 4?
What if you add more weight to the stem?

Be a helicopter engineer today! Ask questions! Have fun!

And remember to head over to the STEM Friday round-up to see what other people are posting.