Archive for July, 2012

This week, we’ve discovered another reason Brock microscopes are so awesome. With no plug to worry about, you can take them outside! We had our after school kid’s crew students pluck specimens from the garden to observe up close. Take a look at our kids’ eye view of some Hinoki False Cypress.

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Last week, our visitors discovered the phenomenon of iridescence on the scales of blue morpho butterfly wings. It turns out iridescence occurs a lot in nature! We can find beautiful examples of iridescence in mother of pearl shells, the feathers of peacocks and ducks, and even on some flies and beetles.

Some iridescent animals use their ability to reflect light to attract a mate. Male Anna’s hummingbirds will manipulate their feathers to produce quick flashes of bright red that they can direct towards a potential mate. Since the red color can only be viewed from a certain angle, the hummingbird nicely avoids also attracting a nearby predator.

Check out the wild and spooky iridescent mating dance of  the “Superb Bird of Paradise” from Papa New Guinea.

After exploring some pictures and videos of iridescence, your students may be ready  to experience it first hand. Your kids have probably been playing with iridescence all their short lives – all you need are bubbles!

Bubbles reflect light off two surfaces of soap sandwiching a layer of water. If the two reflected light wavelengths line up, you perceive a super intense color, this is called constructive interference. If the light waves reflected off the two surfaces don’t line up perfectly, they will cancel each other out, a phenomenon called destructive interference. In destructive interference the light waves become too mixed up and scrambled for your eyes to even perceive; the colors cancel each other out.  The varying thickness of the bubble surface changes which light wavelengths get amplified and which get cancelled out. How many different colors can your students spot on the surface of a bubble? Do the colors change based on the angle of observation?

After exploring iridescence through bubbles, go on a nature walk to see if you can spot any iridescent wildlife.

These iridescent green flies live in the garden at the Brooklyn Children’s Museum.

Starlings, with their iridescent green and purple plumage, are all too easy to spot in New York. They were introduced to Central Park in 1890 by a Shakespeare fanatic who wanted to introduce every bird mentioned in Shakespeare’s plays to New York City. They went from 40 birds to 50 million birds a century later! Read more about their invasive introduction to Manhattan here.

If it’s recently rained, examples of iridescence can even be found on an oily street or in sidewalk puddles!

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Throughout the summer at the Brooklyn Children’s Museum, we hold a public program every Tuesday at 2:30 called “Extraordinary Laboratory.” This inquiry-based  science lab allows kids to take their learning in any direction that suits their interests. We provide microscopes, magnifying glasses, and an array of fascinating specimens on a particular theme. It’s their job to run wild with their own observations and scientific questions. Sometimes we discover answers to their quandaries and sometimes the kids take their questions home as mysteries to be solved with a little library or internet research.

This week, the theme of our lab session was bugs. We offered all sorts of dead bug specimens to observe under a microscope: everything from dragonflies to water beetles, bees to butterflies. The specimen that most captured the junior scientists’ attention was the wing of a blue morpho butterfly. Every time a kid put their eye up to the microscope, we’d get a chorus of “Whoa!” “Wow!” “Awesome!” “So cool!”

A butterfly wing is covered with hundreds of brilliantly colored scales. When the kids handled the wing specimens, they found a bright blue powder left behind on their fingers; the tiny scales had fallen off the wing. Throughout a butterfly’s life, these scales rub off from daily butterfly activities and cannot be regenerated. The brown patches in these pictures show where the  shingle-like scales are missing. One child looked down at their finger and exclaimed “The spots on the wing look like glitter!”

Blue morpho butterflies, like some other species of butterflies, get their brilliant blue color from iridescence rather than pigmentation. Pigment color works by absorbing certain wavelengths of light on the color spectrum and reflecting others back. For instance, the chlorophyll pigment in plants absorbs all wavelengths of light except green which is reflected back to your eye.

Iridescence is special because it’s all about reflecting light waves multiple times. Within each tiny butterfly scale are lots and lots of semi-transparent surfaces for light to pass through and reflect off of. These surfaces are stacked with equal distance between each layer so that each reflected blue light wave lines up perfectly with the other reflected blue light waves, a phenomenon called constructive interference. The result is a bright amplified color!

There is no blue pigment in the scales – that’s right – there is not a single bit of blue pigment in that super bright blue wing! Because what you’re seeing is light bouncing off tiny clear cuticles inside the scale, the color can shift or even disappear depending on how the light is bouncing from the scales to your eye and which light waves are being reflected multiple times in perfect sync! When you look at the butterfly wing from the side, you will see a  shorter wavelength violet color. When you light the wing directly from behind, the blue light waves become completely jumbled with other light waves and the blue color disappears!

Remember our series on biomimicry? Researchers in nanotechnology study blue morpho wings and are attempting to mimic their iridescent scales for use in security. The goal is to create tiny materials that reflect light in the same way and could be used to make counterfeit-proof money, passports, and IDs.

At  $129 a pop, these microscopes are a bit of an investment, but we’ve found them to be durable and really  easy to use for ages five and up. If looking at iridescent specimens through a microscope isn’t an option, don’t fret,  stay tuned to learn how to explore iridescence in other ways!

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Ever see a snake bite in a movie and wonder what’s going on in that cowboy/adventurer/explorer’s body as they race to procure their anti-venom in time? This video shows what just one drop of Russell’s Viper venom does to human blood. Note: This video might be a little scary for younger kids so parents might want to take a look first. Thanks goodness none of the snakes at The Brooklyn Children’s Museum are venomous- we’d never mix toxic fangs with little children! However, we were surprised to find that these snakes may do just as much good as harm for humanity.

Catch those fleshy fangs in the video? Did you know that some snake fangs are so long, they fold back into the snake’s mouth when the snake isn’t striking? Fangs are hollow and connected to two sacs behind the snake’s eyes. When a venous snake strikes, the fangs deliver a large dose of venom to the unlucky prey.

As it turns out, the scary properties of snake venom can also have some life saving medicinal uses. Viper snake venom is used to test for certain blood diseases. Some diseases make people prone to excessive bleeding – their blood is missing the protein that keeps it from clotting or forming scabs. If a drop of snake venom was dropped in a beaker of their blood (like in the above video), their blood would not coagulate into a solid clump in the same way. A drop of viper venom can be used to stop excessive bleeding during surgery or after a major trauma, too!

Alternatively, Malayan Pit Viper venom thins the blood and can be used to break up blood clots in stroke victims. When a blood clot forms in the brain and causes a stroke, doctors try to dissolve the clot and increase blood flow to the brain before more neurons are lost, this can reverse some of the effects of the stroke.

Interestingly, the venom of other snakes like the African mamba affects the nervous system instead of blood and tissues. The venom travels through our blood to the brain where it blocks the chemical signals involved in our most basic human functions- like breathing and circulation. These are the same chemical signals that get interrupted in disorders like asthma, Parkinson’s, and Alzheimer’s. If researchers can break the code of mamba venom, they may understand more about these disorders and come closer to the cures.

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Photos provided by MSG Photos.”

Last week a bright and curious group of kids from the Garden of Dreams Foundation visited the museum. They were joined by some special guest stars from the New York Liberty women’s basketball team and together, we explored solar energy in celebration of the WNBA’s Green Week!

We began our energy investigation by discussing  what makes a building “green”, taking a look at the museum’s solar panels, and observing our solar power Green Threads exhibit. In just a few minutes, our energy experts were able to identify the pros and cons of solar energy. We don’t pollute as much by burning fossil fuels, but how do we produce energy on a cloudy day? The kids observed from our solar exhibit that there is much less electricity output on a cloudy day,  when there’s heavy smog, and at night.

Photos provided by MSG Photos

So they can become future solar energy experts and solve these conundrums, we wanted to give these kids a grasp on electrical circuitry, how electrons move from one place to another. We created our first circuit by joining hands in a circle and having two people in the circle each touch a finger to an electrode on the energy ball. The ball blinks and buzzes when the circuit is complete. The kids discovered how they could create a “switch” by unlinking hands anywhere in the circle and breaking the circuit. They especially enjoyed quick paced high fives that made for a silly sound pattern as the energy ball sputtered and buzzed.

Photos provided by MSG Photos

Our energy students then worked to build their own circuits with a battery as their power source. They knew the materials they would need- a socket, a light bulb, and wires. After fiddling with different wire combinations- Wa La! The light bulbs lit up one by one. For a bigger challenge, the teams tried to make their circuits larger by adding conductive materials. They tested brass buttons, felt, paper clips and beads to see which materials stopped electrons in their tracks and which allowed electrons to flow through.

Photos provided by MSG Photos

After the kids had great circuit success, we moved outside with some portable solar panels to see if we could have the same success with a renewable power source. At first, the sun was blocked by some ominous rain clouds. It had been a cloudy afternoon and we were worried the kids would leave with a skeptical view of solar energy. Our Liberty ladies encourages all the kids to wave their hands and try to blow the clouds away. At last, the sun peaked out from a clouds and our mini machines, propelors in this case, started spinning. With a little patience and help from our very tall guest stars, they harnessed the sun!

Photos provided by MSG Photos.”

These solar circuitry kits are a great investment that you can use again and again. We’d love to hear about any energy experiments you do in your classroom!

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