Archive for November, 2012

Every Wednesday, I teach a science lesson to our 1st grade after-school kids. So far this year, we’ve explored snails, stick bugs, camouflage, and games from around the world. A couple weeks ago, we learned all about polar bears!

Polar bears are the largest land dwelling carnivores. They prey almost exclusively on seals. Surprisingly, when food is plentiful, they’ll only eat the seal’s fatty tissue- found in their brains and blubber- before moving on to the next kill. They are fully stocked with ice-hunting adaptations to make them fierce predators. Their paws have ice-pick claws that never retract and non-slip foot pads covered in tiny bumps that create suction on the ice. Their noses’ have a huge olfactory bulb that can smell a seal in water from a mile away.

Polar Bears are so well insulated that they often have to take dips in the icy water to cool down – they can swim for miles in Arctic water without stopping. Get this – each individual hair on a polar bear is a clear hollow tube. The hair funnels sunlight down to the bear’s black skin where the heat is absorbed and retained under a layer of blubber!

We will be getting out our incredible Polar Bear skin specimen on December 30th for a “Blubber Up!” program all about Arctic animal adaptations. Though I’m glad the importation of Polar Bear hides has been banned in the US (decades after we acquired this specimen), seeing a hide in person is truly awe inspiring. Don’t miss the chance to examine their transparent tube hairs up close!

The after school kids used their new expertise to sculpt a polar bear out of model magic clay. It was interesting to see the kids flattening out their clay before beginning to shape it into a bear likeness. I realized that many of them hadn’t sculpted before, and since we had only been looking at pictures of polar bears, they had trouble conceptualizing a 3-D bear!

We talked about molding a special long neck, strong swimming legs, and had to refer back to some pictures to remember if polar bears have tails or not. They were given a black marker to fill in the eyes, nose, and foot pads.

Since we just had our first snowfall, the kids were able to go outside and collect snow to build real ice dens for their bears! Each kid scooped up a bowlful of snow and shaped the snow to fit a mama bear and one or two cubs. By the end of the class, the dens were melting which was a perfect setup for next week’s topic: Climate change!

Stay tuned to hear about how six year old scientists talk about climate change.

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Snails make the perfect classroom pets. They aren’t terribly high maintenance but they require enough care that students get to play an important role in maintaining a healthy colony.

A fish tank makes an ideal snail enclosure but those can run a little pricey- a plastic bin with a removable lid makes an inexpensive alternative. It should be at least around 20 cm x 20 cm. The bigger your enclosure, the easier it will be to monitor humidity levels. For more tips on building your own tank, check out this site.

You can build the habitat of your snail enclosure as a class project. Collect dirt, rock, leaves,  and sticks. You can even throw in real moss and ferns to help with humidity levels. Bricks, limestone, cement, or old sea shells add a source of calcium that the snails will grind up and use to “build” their shells.

Any gardener would be happy to let you collect plant-eating snails from their garden. Perhaps your class’s snail collecting could involve visits to local community gardens!

Beside the standard scientific observation we covered in our last post, here are some daily chores and activities your students can take turns doing to ensure happy gastropods:

  • Spray down their enclosure. If you don’t keep snails moist with a daily spritz, they’ll seal themselves up in their shell with a film of dried up slime. But don’t water too much — too much moisture and you’ll get stinky mold in the enclosure.
  • Add some fresh lettuce greens to your tank and watch how quickly the snails chomp away. You can try out other fruits and veggies to see what your snails prefer.
  • Have your students devise some experiments to do with your snails. The book Snailology has some some fun quandaries to work with:
    • Build a maze! Can find their way around corners and through obstacles?
    • Snail circus! Build a snail tight rope with some string and watch the snails race across. Do they “walk the line” or prefer a more windy path?
    • Test the weight bearing power of a snail! Tape a string and a penny to their shell. Can they pull a penny? Can they pull a quarter?
    • Are snails attracted to darkness or will they seek out the light?

    Let us know if you have snail success!

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One of our new school programs this year is called “A Snail’s Place.” This program was born when we discovered that kids don’t just  dig snails, they love them. Whenever we bring out one of these plant-devouring gastropods, which we happily collect from our own garden, kids become transfixed in close observation. The excitement of a snail emerging from its shell and poking out one tentacle feeler at a time, the tactile sensation of their slimy foot moving across their hand, and the surprisingly quick responses of snails can hold kids’ attention for twenty minutes (that’s like two hours in kid-minutes). Snail observation also escapes the fear factor that comes with observing other bugs like our Madagascar hissing cockroaches.

At BCM, we are always working to make our programs less didactic and more inquiry based! Rather than delivering all the interesting snail factoids to passive students, we want our students to feel empowered to do their own research and share their findings. We composed a snail resource sheet for the kids to explore. The students can read and share the facts they find most interesting and compare their live snails to the anatomical diagram. Can they find their eye spots? Can they find their spiral shell? Can they find their breathing hole?

We collect scientific observations and questions as the students observe. Some questions we’ve collected from the public include: Are snails good climbers? How do you think they move? What’s the purpose of that slime? Why do they come out in the rain? What kind of habitat do you think they like?

Our final activity is to review the things that snails need in their environment to be happy. The kids venture outside to collect sticks, rocks and leaves to build the perfect snail habitat! They observe how the snails interact with their new environment. Do they seek out the shade or the light? Do they like to eat all kinds of leaves? The students add their most successful snail architecture to our permanent snail enclosure.
Stay tuned for tips on keeping your own classroom snail tank!

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