| ||||||||||||||||||||||||||||
|
Friday, July 27, 2012
July 2012 Newsletter
Making boats: hull design
A friend recently invited me to her house to do a science experiment involving the stream that runs through her property. Well, that sparked about a million ideas! However, I thought we'd start with a fairly simple concept: boatmaking.
More specifically I wanted to focus on hull design: the watertight body of a ship or boat that meets the waterline. Hulls are generally divided into two categories: displacement hulls and planing hulls. Displacement hulls have a large underwater profile and tend to move slowly. Planing hulls are meant to ride high along the waterline, and can go fast.
The shape of bottom of the boat is key to how it functions in water. Depending on what you want to do, you can build a boat with anything from a flat bottom to a rounded bilge to a hard chined V-shape. And of course, you can combine these basic shapes into a wide variety of composite shapes. Finding a balance that allows for a boat to carry the needed load while being able to move quickly and accurately is a tricky thing.
To further adjust the hull, a designer can add a keel to add stability or a rudder to help steer. You can also easily adjust the bow of the boat, the front or forward part of the hull. Changing this shape affects how well the boat cuts through the water, by reducing its resistance.
When you ask a child to draw a boat, they often focus on everything above water. After all it's what you can see easily. So getting them to think about the hull, and how it can affect the way a boat actually works, is a great change in perspective. And it makes for a fun engineering design project.
For materials I wanted something easy to manipulate, basically waterproof, and inexpensive. I like using things you can buy in the supermarket, because it gives kids the opportunity to keep experimenting at home without the need for special equipment. So I settled on wax-coated paper cups, an assortment of tapes and a stapler. I also provided some aluminum foil, but explained that they couldn't use the foil as their main design component.
I love working with kids, because you never know what they'll do. I assumed they'd cut up the cups, maybe use the flattened sides to build their designs. But instead they started creating displacement hulls and pontoon-style designs using the whole cups. Soon they were sharing designs, adjusting and improving their boats.
Once everyone was ready, we headed down to the stream to test our boats. First we used fishing weights to see how much load each boat could hold. Some were able to handle a pound or more! Then we let the boats take a run down an area of "rapids" while we timed the run with a stopwatch to see which moved most quickly. Several crossed the finish line in under 10 seconds, one in 7 seconds!
I was impressed with their determination. It started to rain when we headed down to the stream, but everyone stayed to test their boats. (What the heck, we were wet anyway!) However, the weather didn't give us a lot of opportunity to develop our boat design based on what we learned.
For students that want to extend the project, a soft wood like pine can be used to carve a hull. They can also experiment with buoyancy by using various types of wood in the same shape and size to see how the density affects how they float.
There is a lot of physics to be explored with boat design. We only had the chance to touch the tip of the iceberg. But for an overview of all the amazing engineering involved in boat design, check out the video below.
Or if you have an older, computer-savvy child, they may want to give some CAD a try with this virtual hull designer.
More specifically I wanted to focus on hull design: the watertight body of a ship or boat that meets the waterline. Hulls are generally divided into two categories: displacement hulls and planing hulls. Displacement hulls have a large underwater profile and tend to move slowly. Planing hulls are meant to ride high along the waterline, and can go fast.
The shape of bottom of the boat is key to how it functions in water. Depending on what you want to do, you can build a boat with anything from a flat bottom to a rounded bilge to a hard chined V-shape. And of course, you can combine these basic shapes into a wide variety of composite shapes. Finding a balance that allows for a boat to carry the needed load while being able to move quickly and accurately is a tricky thing.
To further adjust the hull, a designer can add a keel to add stability or a rudder to help steer. You can also easily adjust the bow of the boat, the front or forward part of the hull. Changing this shape affects how well the boat cuts through the water, by reducing its resistance.
When you ask a child to draw a boat, they often focus on everything above water. After all it's what you can see easily. So getting them to think about the hull, and how it can affect the way a boat actually works, is a great change in perspective. And it makes for a fun engineering design project.
For materials I wanted something easy to manipulate, basically waterproof, and inexpensive. I like using things you can buy in the supermarket, because it gives kids the opportunity to keep experimenting at home without the need for special equipment. So I settled on wax-coated paper cups, an assortment of tapes and a stapler. I also provided some aluminum foil, but explained that they couldn't use the foil as their main design component.
I love working with kids, because you never know what they'll do. I assumed they'd cut up the cups, maybe use the flattened sides to build their designs. But instead they started creating displacement hulls and pontoon-style designs using the whole cups. Soon they were sharing designs, adjusting and improving their boats.
Once everyone was ready, we headed down to the stream to test our boats. First we used fishing weights to see how much load each boat could hold. Some were able to handle a pound or more! Then we let the boats take a run down an area of "rapids" while we timed the run with a stopwatch to see which moved most quickly. Several crossed the finish line in under 10 seconds, one in 7 seconds!
I was impressed with their determination. It started to rain when we headed down to the stream, but everyone stayed to test their boats. (What the heck, we were wet anyway!) However, the weather didn't give us a lot of opportunity to develop our boat design based on what we learned.
For students that want to extend the project, a soft wood like pine can be used to carve a hull. They can also experiment with buoyancy by using various types of wood in the same shape and size to see how the density affects how they float.
There is a lot of physics to be explored with boat design. We only had the chance to touch the tip of the iceberg. But for an overview of all the amazing engineering involved in boat design, check out the video below.
Or if you have an older, computer-savvy child, they may want to give some CAD a try with this virtual hull designer.
Monday, July 23, 2012
Marshmallows flying!
It's just not summer if I don't break out the catapults and launch marshmallows around the Farmers' Market. So the other week, I brought this easy, classic science activity to Blairstown.
The design for this tongue depressor catapult from a really fun book called Mini Weapons of Mass Destruction by John Austin. I know it sounds dangerous, but with a little parental supervision most designs are quite safe for kids. And so much fun! It's engineering disguised as mayhem!
The design for this tongue depressor catapult from a really fun book called Mini Weapons of Mass Destruction by John Austin. I know it sounds dangerous, but with a little parental supervision most designs are quite safe for kids. And so much fun! It's engineering disguised as mayhem!
The basic construction is simple. You stack seven tongue depressors together and use two rubber bands on either end to hold them together. Then take two depressors and attach them with a rubber band on one end. Spread the two depressors into a "V" shape, and insert the stack lengthwise to make a "T" shape. Use another rubber band to secure the depressors together into your catapult. (The book gives clear, step-by-step instructions with diagrams.) For the original design, the author suggests using a hot glue gun to attach a bottle cap as a launcher, but I find it easier to just attach a disposable spoon with another rubber band or two. No electricity needed!
You can make the catapult with popsicle sticks too, though I find a stack of just five is enough. The popsicle sticks are thicker, and a bit harder to work with, but you can get the job done. I also like to make the coat hanger slingshot from the book too, and challenge kids to see which works better. The book has a whole chapter devoted to slingshots, catapults and trebuchets, so kids can have a lot of fun comparing results.
Then it's time to load a mini-marshmallow and get shooting! I like to give kids dixie cups that they can use to make towers. It's fun to knock them down. Dominos are also fun! For some Angry Birds action, paint your marshmallows red and green (or use leftover Christmas-themed ones, like I did here).
Another great catapult design that is easy to make and fun to tinker with comes from a great YouTube video I found years ago. This shoebox catapult is always a hit.
Spray paint and other watercolor fun
This week at the Farmers Market I decided to do something fun and messy: spray painting! But don't worry it's not what you think!
Obviously, I wanted to make sure my paints were non-toxic and washable, so I made my own. It's easy! I gathered up some old markers from around the house, used pliers to pop off the back, pulled out the felt and put it into an inexpensive 8 oz. spray bottle. Then I added water and gave it a good swish. Within minutes I had a cheap bottle of parent-approved spray paint ready to go. I let the colors sit over night to make sure they were nice and bright before using them. In other words: FREE PAINT! Great way to reduce, reuse and recycle.
At the market, I offered everyone stencils. It takes a light touch, but you can get a nice affect by spray in the paint over them. Of course, not everyone is interested in precision. Some kids wanted to just have fun mixing colors and seeing what happened! That's why I like to make sure I have all the primary colors available.
One regular KLC buddy, Brenden, mixed stencils, the spray paint, a spray bottle of water and washable markers to make some really neat artwork.
To look at the process from the other side, I offer kids coffee filters. They used washable markers to make designs, then sprayed with plain water, causing the ink to spread and blend. It's a lot of fun. I especially like using the black marker, because all the pigments separate, showing the blues and greens that make up the black ink. This is a really fun way to introduce children to chromatography!
For older students, you can use permanent markers, like Sharpies, and alcohol to create the same effects. Try it on fabric and you can make awesome faux tie dye shirts!
Obviously, I wanted to make sure my paints were non-toxic and washable, so I made my own. It's easy! I gathered up some old markers from around the house, used pliers to pop off the back, pulled out the felt and put it into an inexpensive 8 oz. spray bottle. Then I added water and gave it a good swish. Within minutes I had a cheap bottle of parent-approved spray paint ready to go. I let the colors sit over night to make sure they were nice and bright before using them. In other words: FREE PAINT! Great way to reduce, reuse and recycle.
At the market, I offered everyone stencils. It takes a light touch, but you can get a nice affect by spray in the paint over them. Of course, not everyone is interested in precision. Some kids wanted to just have fun mixing colors and seeing what happened! That's why I like to make sure I have all the primary colors available.
To look at the process from the other side, I offer kids coffee filters. They used washable markers to make designs, then sprayed with plain water, causing the ink to spread and blend. It's a lot of fun. I especially like using the black marker, because all the pigments separate, showing the blues and greens that make up the black ink. This is a really fun way to introduce children to chromatography!
Thursday, June 28, 2012
Silkworms
Caitie is tutored by a lovely woman, Lorna Wooldridge. She's kind, caring, and understanding while mixing in a good dose of appropriate motivation and discipline. In addition to all the great work she's done with Caitie on reading, Lorna also has a variety of other interests including butterflies and moths.
Each year Lorna raises monarchs and other butterflies. Thanks to her, I've had the opportunity to see some caterpillars I'd never laid eyes on before. This spring Lorna raised Zebra silkworms from eggs she got from Michael Cook, who runs an excellent website on silkworms.
The caterpillars are strikingly lovely with vivid markings. As they get ready to spin their silk cocoon, they prefer a close environment, and toilet paper rolls are perfect. Since Lorna was running short, I offered a bag, as I always have lots. As thanks, she was kind enough to give us several cocoons!
The girls and I anxiously awaited moths for a few weeks. Rather than stifle (kill) the cocoons, as is commonly done to preserve the silk, we let the silkworms complete the lifecycle.
Yesterday the moths emerged! We were so excited! Most of the moths were fine, two males and two females. However, the first to arrive had damaged wings and trouble moving. And one cocoon has yet to yield a moth. The healthy moths set about mating pretty quickly, laying eggs soon afterwards. They're still pairing and laying today.
These guys will live for a just a few days, since they don't have mouths. Then we'll store the eggs until next spring, and hopefully, begin the process again!
If you're local to Northwest NJ, and would like to meet Lorna and learn more about her experience raising butterflies and moths, please be sure to attend her Monarch Migration Workshop on July 6 at the Catherine Dickson Hofman Branch of the Warren County Library in Blairstown, NJ.
Each year Lorna raises monarchs and other butterflies. Thanks to her, I've had the opportunity to see some caterpillars I'd never laid eyes on before. This spring Lorna raised Zebra silkworms from eggs she got from Michael Cook, who runs an excellent website on silkworms.
 |
|
This zebra silkworm appears to inspect its new home before entering the nest.
Read more: http://www.post-gazette.com/stories/local/neighborhoods-north/fifth-graders-bring-scientific-method-to-madness-338139/#ixzz1z5avpbv0
|
The caterpillars are strikingly lovely with vivid markings. As they get ready to spin their silk cocoon, they prefer a close environment, and toilet paper rolls are perfect. Since Lorna was running short, I offered a bag, as I always have lots. As thanks, she was kind enough to give us several cocoons!
The girls and I anxiously awaited moths for a few weeks. Rather than stifle (kill) the cocoons, as is commonly done to preserve the silk, we let the silkworms complete the lifecycle.
Yesterday the moths emerged! We were so excited! Most of the moths were fine, two males and two females. However, the first to arrive had damaged wings and trouble moving. And one cocoon has yet to yield a moth. The healthy moths set about mating pretty quickly, laying eggs soon afterwards. They're still pairing and laying today.
These guys will live for a just a few days, since they don't have mouths. Then we'll store the eggs until next spring, and hopefully, begin the process again!
If you're local to Northwest NJ, and would like to meet Lorna and learn more about her experience raising butterflies and moths, please be sure to attend her Monarch Migration Workshop on July 6 at the Catherine Dickson Hofman Branch of the Warren County Library in Blairstown, NJ.
Sunday, June 24, 2012
A Confession
Recently, I was cruising Facebook, as I too often do, when I came across the following meme. It featured Neil deGrasse Tyson, so naturally I stopped in my tracks and read it. Because he is just THAT cool.
Anyway, I confused. I mean, the sun is yellow, right. That's what the textbook told me. And that's what I taught. The sun is a yellow star.
It was at this point that I started to freak out a little See, Tyson is one of my favorite scientists; he's a crazy smart guys. I trust him. He he says the ain't yellow, then I have a major problem. Because I'm been teaching it WRONG!
Now, as to the confession: My earth science isn't that strong. Stronger, perhaps, that the average American, especially when it comes to soil science, but that isn't good enough. I'm a scientist. I'm a TEACHER. I have a responsibility to be correct as often as possible, so that I'm not passing on half-truths to my students. This is a big deal to me. It's why I read a lot of non-fiction and love professional development.
That said, the wonderful thing about learning is that it never stops. So off I went to do some research. I learned that the sun only appears to be yellow to us due to the Earth's atmosphere. The atmosphere scatters the blue light, causing our sun to look more yellow on Earth than it would from space. It is, in fact, a white star, with a temperature of approximately 6,000 Kelvin. Of course, because the sun has layers of different temperatures, each sends a different wavelength of light and what we see if often this combination, interpreted by our eye, which is itself limited.
Of course, I feel better that lots of people are unsure about the topic and that there is still debate on the matter. I just think that next time I teach the sun, especially middle school or older, we'll start with the color as a question and challenge so that we can explore how complicated the answer really it.
So that is what I learned today.
Anyway, I confused. I mean, the sun is yellow, right. That's what the textbook told me. And that's what I taught. The sun is a yellow star.
It was at this point that I started to freak out a little See, Tyson is one of my favorite scientists; he's a crazy smart guys. I trust him. He he says the ain't yellow, then I have a major problem. Because I'm been teaching it WRONG!
Now, as to the confession: My earth science isn't that strong. Stronger, perhaps, that the average American, especially when it comes to soil science, but that isn't good enough. I'm a scientist. I'm a TEACHER. I have a responsibility to be correct as often as possible, so that I'm not passing on half-truths to my students. This is a big deal to me. It's why I read a lot of non-fiction and love professional development.
That said, the wonderful thing about learning is that it never stops. So off I went to do some research. I learned that the sun only appears to be yellow to us due to the Earth's atmosphere. The atmosphere scatters the blue light, causing our sun to look more yellow on Earth than it would from space. It is, in fact, a white star, with a temperature of approximately 6,000 Kelvin. Of course, because the sun has layers of different temperatures, each sends a different wavelength of light and what we see if often this combination, interpreted by our eye, which is itself limited.
Of course, I feel better that lots of people are unsure about the topic and that there is still debate on the matter. I just think that next time I teach the sun, especially middle school or older, we'll start with the color as a question and challenge so that we can explore how complicated the answer really it.
So that is what I learned today.
Monday, June 18, 2012
Bubbles: Art, Science & Mentos
About a week ago I decided that bubbles would be my theme for the Blairstown Farmers Market. I mean, bubbles are a clear winner on a lovely spring day at the market. How could I resist?
First things first: the bubble mix. You can buy some, sure. That's quick and easy, but a bit expensive, especially for large quantities. So I made my own using dish soap, water and bit of vegetable glycerin. Recipes abound online, but I like about a 1:12 ratio of detergent to water with about a teaspoon or two of glycerin per cup of solution, depending on the detergent I've used. You can use corn syrup or sugar to make the bubbles last longer, but I find that makes the mix really sticky and attracts more insects, so I like glycerin instead. No matter what, your bubble mix will get better if you let it sit open overnight, especially if your detergent contains alcohol. That said, I usually don't have the patience to wait.
Great! You've got bubble mix! Now what? Get out the pipe cleaners! Let kids make bubble wands using the pipe cleaners. They'll often make all kinds of creative designs -- heart shaped tops and two-color sticks. After a bit, I like to ask if they get square bubbles form a square wands. Kids will laugh at me and say, "Of course not! You always get a round bubble!" That's when I like to ask, "Why?"
Make them think about it for a while.
See the Universe is an amazing thing, and it like to be efficient. A sphere allows the greatest volume to be trapped within the smallest surface area. So, you can trap the most air inside a round bubble, as opposed to a square, triangle or trapezoid using the same amount of bubble solution. A bubble wouldn't float long if it was bogged down by extra bubble mix! The surface tension of the bubble mix pulls the bubble into that classic shape. The only way to get a bubble to take another shape is to surround it by other bubbles. If you're looking for some wonderful geometrical studies, calculating and modeling the volume to surface area ratios can be a lot of fun.
Now that you've got bubble mix, there are a lot of fun things you can do. For example, there are instructions for giant bubbles and bouncing bubbles. A friend at the market showed us how to create a bubble foamer, which was a huge hit. We just cut a plastic water bottle to separate the top "funnel" from the bottom. We attached a rag to the open end of the funnel with a rubber band. Dip the rag in bubble mix and blow through the drinking end of your water bottle. Tons of fun!
Now, let's move on to art! We did a really simple bubble print project that's easy to set up and really neat. In bowls, I mixed 2-3 tablespoons of washable, non-toxic tempera paint (bright colors work best -- blue, green, orange, red), 1 tablespoon of dish detergent and a 1/2 cup of water. Stir gently. Then, using a straw, blow bubbles in the mixture, letting them rise well above the bowl. Then gently lower a piece of paper onto the bubbles. As they pop they'll leave colorful bursts. You can keep adding bubble prints to fill your page, using many colors and experiment with how fast or slow you blow your bubbles (it can change the size of the bubbles). You can also dip your bubble wand into the mixture and blow onto the paper to create fun patterns that way!
To finish up the day, we made some bubbles in other ways. We combined vinegar and baking soda, a classic chemistry experiment that yields lots of bubbles as carbon dioxide is released. But the real hit was Mentos in diet cola, a la Steve Spangler and Mythbusters The set up is easy: Open a 2-liter bottle of inexpensive diet cola; unwrap a 6-pack of classic Mentos; use index cards to create a tube to hold the Mentos and a slip to cover the top of the bottle; place the slip over the bottle top, the tube on the slip and add the Mentos. When you're ready, pull the slip out and let the Mentos drop into the cola. Then get out of the way quickly!
The result to pretty awesome. Why it works is somewhat up to debate. The links above will review some of the best ideas put forth in detail. Basically the idea is that the dissolving candy breaks the surface tension of the soda, which is holding back the expansion of the carbon dioxide bubbles within. The pits all over the candy then provide nucleation sites for bubbles to attach. The heavy candies fall to the bottom of the bottle, forcing the bubbles -- and the soda -- to come gushing out of that small opening, forming a geyser! You can vary the reaction in many ways to create a super fun (and potentially messy) experiment.
First things first: the bubble mix. You can buy some, sure. That's quick and easy, but a bit expensive, especially for large quantities. So I made my own using dish soap, water and bit of vegetable glycerin. Recipes abound online, but I like about a 1:12 ratio of detergent to water with about a teaspoon or two of glycerin per cup of solution, depending on the detergent I've used. You can use corn syrup or sugar to make the bubbles last longer, but I find that makes the mix really sticky and attracts more insects, so I like glycerin instead. No matter what, your bubble mix will get better if you let it sit open overnight, especially if your detergent contains alcohol. That said, I usually don't have the patience to wait.
Great! You've got bubble mix! Now what? Get out the pipe cleaners! Let kids make bubble wands using the pipe cleaners. They'll often make all kinds of creative designs -- heart shaped tops and two-color sticks. After a bit, I like to ask if they get square bubbles form a square wands. Kids will laugh at me and say, "Of course not! You always get a round bubble!" That's when I like to ask, "Why?"
Make them think about it for a while.
See the Universe is an amazing thing, and it like to be efficient. A sphere allows the greatest volume to be trapped within the smallest surface area. So, you can trap the most air inside a round bubble, as opposed to a square, triangle or trapezoid using the same amount of bubble solution. A bubble wouldn't float long if it was bogged down by extra bubble mix! The surface tension of the bubble mix pulls the bubble into that classic shape. The only way to get a bubble to take another shape is to surround it by other bubbles. If you're looking for some wonderful geometrical studies, calculating and modeling the volume to surface area ratios can be a lot of fun.
Now that you've got bubble mix, there are a lot of fun things you can do. For example, there are instructions for giant bubbles and bouncing bubbles. A friend at the market showed us how to create a bubble foamer, which was a huge hit. We just cut a plastic water bottle to separate the top "funnel" from the bottom. We attached a rag to the open end of the funnel with a rubber band. Dip the rag in bubble mix and blow through the drinking end of your water bottle. Tons of fun!
Now, let's move on to art! We did a really simple bubble print project that's easy to set up and really neat. In bowls, I mixed 2-3 tablespoons of washable, non-toxic tempera paint (bright colors work best -- blue, green, orange, red), 1 tablespoon of dish detergent and a 1/2 cup of water. Stir gently. Then, using a straw, blow bubbles in the mixture, letting them rise well above the bowl. Then gently lower a piece of paper onto the bubbles. As they pop they'll leave colorful bursts. You can keep adding bubble prints to fill your page, using many colors and experiment with how fast or slow you blow your bubbles (it can change the size of the bubbles). You can also dip your bubble wand into the mixture and blow onto the paper to create fun patterns that way!
The result to pretty awesome. Why it works is somewhat up to debate. The links above will review some of the best ideas put forth in detail. Basically the idea is that the dissolving candy breaks the surface tension of the soda, which is holding back the expansion of the carbon dioxide bubbles within. The pits all over the candy then provide nucleation sites for bubbles to attach. The heavy candies fall to the bottom of the bottle, forcing the bubbles -- and the soda -- to come gushing out of that small opening, forming a geyser! You can vary the reaction in many ways to create a super fun (and potentially messy) experiment.
Subscribe to:
Posts (Atom)