Thursday, October 25, 2012

Seed dispersal - predictions, estimations, and fractions

Birches students have been closely investigating seeds for the last two weeks.  We made several interesting observations while on nature walks, including many of the different ways that plants have to spread their seeds. Using plants and seeds that we had collected, students learned to categorized their seeds based on the mechanisms of dispersal: wind, water, animals/humans, gravity, and mechanical force. We also tried our hand at designing our own seeds and testing them by gravity dispersal. And Kate H. found an excellent video to share with us as well.

We talked about why plants expend so much energy on making extra seeds, and wondered if size of the plant/fruit determined how may seeds are made.  Peaches, apples, pumpkins, and strawberries were compared and we decided that fruit size is not necessarily a good determinant of how many seeds a plant will produce.

Just before we sliced open a sugar pumpkin, students made predictions about how many seeds we would find inside, estimates ranged from 500 to 50 seeds total.  Bisecting the pumpkin, we scooped out the seeds of one half of the fruit.  Each student was given a fraction of seeds to count by themselves.  Students grouped their seeds on plates in sets of 5 seeds/group and then added all sets of five to give us their totals.  When it came time to estimate how many seeds we would find in the remaining half of the pumpkin, we were much closer to the actual number.  Plotting a bar graph together we noticed that our first seed number guesses were not as accurate as our second predictions were.  We decided that having a little more information and experience, from counting the first half of the pumpkin, provided us with enough confidence to make more accurate estimations about the quantity of seeds inside.

I think we were all surprised to find that half of our small pumpkin contained 399 seeds and once we added the remaining portion we found that the pumpkin contained 470 seeds total!

From seeds we are moving on to the animals who eat them.  Over the winter we will participate in project feeder watch.  Making our own feeders, we will have an opportunity to become citizen scientists, learn to identify species, talk about migration patterns, how weather may effect our count, and to record data.

Sunday, October 7, 2012

Our listening walk

Last week, friends took me on one of their favorite trails near Birches School.  After almost a full week of rain, we appreciated the warmth of our "Science Friday" all the more and after reading Under One Rock: Bugs, Slugs, and Other Ughs by Anthony D. Fredericks, we decided to take our science lesson outdoors.

Our mission was to not only enjoy a beautiful autumn walk through the forest together but to also play a listening and noticing game. With particular focus on the many bug communities we could find just outside the school house, we had great fun describing habitat types and the invertebrates we found living in them.  While I scribbled notes, the children called out the names of animals they were seeing, as well as the noises they were hearing on our nature walk.

We were rewarded immediately on our hike with a plethora of spider web viewing, made even more picturesque by the morning dew clinging to their silk outlines:  spiral orb webs, tangle webs, and tubular webs; housing what appeared to include - orb weavers, cobweb spiders, jumping spiders, sac spiders, ground spiders, and grass spiders.  Friends brought up some excellent wonderings, including: "How long does it takes the spider to build its web?" and "Do spiders have to make a new web every day?"

Some spiders do make a new home daily, eating the old web, resting briefly, and then building a new web in the early evening, just in time for their nightly hunting spree.

While continuing our walk through a field, one friend wanted us to stop and listen to the crickets he was hearing. He had also caught one to show us (I thought crickets were nocturnal) and pointed out that the cricket was missing one leg! "Could he still sing?" and "What do crickets eat?" We had a chance to talk about omnivores and notice the combs on it's wings where male crickets produce their sound by rubbing their wings against each other or by rubbing their wings against their legs, so I guess the missing leg would not prevent him from chirping after all.

Stopping to count the rings of an old tree stump just beside a stone wall, friends noticed an extra large toad at the base; I almost missed it! The camouflaged coating blended in with the tree bark perfectly.

As we made our way deeper into the forest, one of our friends pointed out a large fallen tree that had turned into a rotting log. When she bent down to touch the surface, tiny pieces easily broke off and dissolved between her fingers.  This gave us a nice chance to discuss microorganism habitats too - bacteria and fungi, and the process of decomposition/decay that contribute to generating more soil.

Each week as we use our nature-classroom, I am eager to broadcast (to my friends in the early education community) about the fantastically rich teaching material that nature provides us with; the unparalleled opportunities for critical exploration, countless inquiry-based investigations, and the child-driven lessons that will keep them engaged with learning over their lifetime.