May 11

The water cycle is one of the first atmospheric phenomena to be presented in elementary school science. It offers a universally accessible opportunity for young students to construct an understanding of the natural world from their own observations. Primary school children’s experiences with rain, clouds, fog, steam, and water droplets on the outside of soda cans can be attached to scientific language: condensation, precipitation, and evaporation.

In later years, this process is examined in greater detail. In our sixth grade, the three familiar vocabulary words form the basis of a list of more than a dozen terms, and the sequence of stages gains a more complex title: the hydrologic cycle. In the past couple of weeks, our students have learned about the phases and forms of water as it exists above the ground, on the Earth’s surface, and below the ground. They have studied aquifers, water tables, infiltration, permeable and impermeable surfaces, groundwater, runoff, discharge and recharge.

“Teaching the vocabulary has been really interesting,” Ms. Moriarty reflected the other day. “Once I started introducing the more complex terms, the students’ comprehension of all of the stages expanded.” To enhance their learning, the class has been conducting a series of mini-experiments. One of these investigations involves evaporation: four cups filled with equal amounts of liquid were placed in different locations in the room. Two cups contain plain water; one sits in a well-lit window, and the other is tucked into a dark shelf. Another cup contains salt water, and the fourth contains vinegar. Each day, the cups are weighed on a digital scale and the students record the change in mass from the previous day.

This data collection corresponds directly to the math unit about rates and ratios that is underway, allowing the class to engage in conversations that enhance both disciplines. After 24 hours, the water in the cup in the window was reduced by eight milliliters, and the cup on the shelf had lost six milliliters. “What’s the rate of evaporation?” Ms. Moriarty asked. “Eight milliliters in 24 hours comes to one milliliter in three hours,” one student responded immediately. “So, should we be measuring the cups twice a day?” the teacher prompted. “No,” came another reply. “That’s an average rate.” The first student added, “but if it keeps evaporating eight milliliters a day, the water should be gone in 13 days.”

“That’s not just a guess,” Ms. Moriarty said enthusiastically. “He used math to make that estimate. And now, we can use an inverse relationship to make a prediction about how long it will take for the water in the cup on the shelf to evaporate completely.” Eagerly, students called out answers, following along as Ms. Moriarty constructed a series of computations on the board based on the following mathematical premise:

If Cup B evaporates ¾ as quickly as Cup A, it will take 4/3 as long for Cup B to evaporate completely.

May 4

One of the many gratifying aspects of being a teacher is the opportunity to “save up” ideas, with the knowledge that they will come in handy at just the right moment. Last month, Mr. Smith pulled one of those ideas out of his own memory bank and shared it with a group of seventh and eighth graders, who eagerly embraced the challenge. They spent the next four weeks bringing a vision to reality.

Mr. Smith’s woodworking project was inspired by an unusual cell phone commercial that Mr. Downing shared via e-mail with the entire faculty last year. Japanese artist Kenziro Matsuo devised an elegant, yet simple, slanted wooden xylophone that was assembled in the beautiful forest of Kyushu. A wooden ball rolling down the device strikes each bar with enough force to elicit a note. The keys of the xylophone are tuned to play Bach’s Cantata 147 (Jesu, Joy of Man’s Desiring). Mr. Smith appreciated the precision of the instrument as well as its engineering and aesthetic components. He wondered if a group of BDS middle school students could accomplish something similar. When he showed the video to his students, they seized the opportunity to design and build their own large-scale (no pun intended) xylophone.

The work began with a prototype: a ten-foot span of one-inch by three-inch boards, cut to varying lengths to produce different notes. One student contributed his exceptional musical sense to the effort, spending two class periods determining the necessary dimensions to generate different pitches within an octave. Once the measurements had been established, the students got to work cutting and arranging their keys. They made 30 sets of eight notes and assembled their keys as a series of scales.

Engineering the xylophone required precise balance and symmetry. The team employed a boat-building technique known as “winding,” which involves tightening screws from both ends of a plank in order to align it at a perfect horizontal. Each of the 240 boards on the full-scale 50-foot xylophone was attached using this method. The entire instrument is arranged at a 15° angle, which the students found to be the necessary slope to propel a ball from top to bottom. Every key is set exactly three inches from its neighbors, and all of the keys are positioned with a one-inch pitch to allow the ball to strike the note and roll to the next bar.

The finished product was unveiled last week and was mounted on the slope behind Claflin Field. Its outdoor location seems ideal, and the variations created by wind and natural forces add to the organic nature of the tune the xylophone plays. A group of faculty members gathered to admire it on Friday afternoon, delighted by the level of engineering, artistry, and design that our students had demonstrated with the support of a thoughtful teacher and an engaging idea.

* A video of the middle school xylophone will be available on bdsnet, and everyone is invited to visit the instrument.

April 24

In his 1999 work Intelligence Reframed: Multiple Intelligences for the 21st Century, psychologist Howard Gardner considers several new categories as potential additions to his original list of seven multiple intelligences. One, in particular, stands out: “naturalist intelligence,” which “enables human beings to recognize, categorize and draw upon certain features of the environment.” Gardner argues that skill in this area is valued among cultures around the world.
Naturalist intelligence has been on full display at BDS this week, as everyone in the building has embraced the purpose of Earth Day, which occurred last Sunday. From ongoing curricular efforts to event-specific activities to informative bulletin boards and environmentally conscious suggestions posted throughout the school, we have all been inspired to think a little more about our responsibilities to the planet. Happily, our Kindergartners started the week with a song that brought together the broad spectrum of aptitudes related to naturalist intelligence.
If you love our world, clap your hands, began the song, to the tune of “If You’re Happy and You Know It.” Each verse introduced a new concept: Planting trees, recycling, and doing our part were all repeated in joyful chorus by the children. After singing the song, the students discussed the meanings of the words. “What are some ways that we can help take care of our world?” asked Ms. Coderre. Many ideas came forward, indicating just how much these young people understood stewardship of the planet and how much they have been noticing in school. One suggestion, “eat all your food,” might have seemed a bit unexpected, except for the fact that the 1st through 8th graders are involved in an exciting challenge to reduce food waste during lunch.
When the Kindergartners talked about trees, they discussed the importance of oxygen, the solid homes that trees provide for animals, the shade they make, and the ways that trees’ root systems can help clean the soil. Our second graders got a first-hand view of trees in action during a trip to Habitat on Wednesday. They saw full-sized trees serving as homes to animals, seedlings growing out of rich soil, and fallen leaves providing compost for new plants.
The “Love Our World” song also includes a stanza about recycling. There may be no better, or more essential, demonstration of this aspect of environmental consciousness than our 3rd graders’ dedication to collecting and organizing the barrels of paper, plastic, and cardboard that accumulate in a busy school. At the end of their song, the Kindergartners repeated the phrase, “do your part.” This statement summed up the efforts that all our entire community has embraced— “lights off” days; “paperless day” in 4th grade; the thoughtful pages about taking care of the world written by 1st graders; earthworm castles in Pre-K; and larger curriculum units about water (6th grade) as well as organisms and ecosystems (7th and 8th grades). Although Earth Week is over, our efforts will continue far into the future.

April 13

What makes a good habitat for a living thing?

As the second graders will tell you, the answer to that question is, “it depends.” The children have been learning about the conditions all living things need for survival. Earlier this week, they sat down with Ms. Shamburg and Mrs. Fox and listed important requirements for sustaining life: food, air, water, sunlight, and shelter. As they considered the needs of organisms such as humans, plants, and fish, the students talked about how they would define “shelter” for each of those life forms.

Humans, the children decided, need homes that have roofs. Humans also need a way to control temperature, and walls to protect them from rain and dangerous animals. “What about fish?” Ms. Shamburg asked. After some thought, one student responded, “The ocean is a kind of roof for fish.” Another child provided a detailed explanation of the way coral reefs and seaweed provide protection and shelter for fish.

When the conversation shifted to plants, there was some curiosity about whether plants needed shelter. After a brief discussion about the idea that some plants grow better in greenhouses than outside, the students realized that most plants (such as trees, grass, and vegetables) grow outdoors. The teachers posed a few questions, which led to further thoughts about habitats and adaptations. Ideas flew about the ways that organisms thrive in different kinds of environments.

Ms. Shamburg presented a surprising new “organism” for the children to consider: a cup of cherry gelatin. “If we were going to try to protect this organism outdoors, what kind of shelter would we want to find?” she asked. Hands flew as children suggested hiding spots, conditions, materials, and challenges for sheltering the gelatin. The teachers divided the class into small teams of naturalists. Each squad made a plan and decided on a location in the woods behind the tennis courts where they would leave their test sample overnight. A cover or a roof was one of the conditions that everyone wanted. Some children were concerned about the gelatin being discovered and eaten by people walking past the samples. Other students shared their thoughts about insect infestations, hungry animals, and warm temperatures. Everyone proceeded outside, and the cups were carefully placed in the selected spots. Back in the classroom, the students opened their science journals to record a description of their shelter spot and predictions about the outcome of the experiment.

How did the gelatin cups survive? The second graders will be glad to share their results, along with their new ideas about habitats, living conditions, and the ways that living things survive in nature.

March 30

Have you been worrying about your biotic relationships lately?

Have no fear. The seventh graders have everything under control. Their most recent research projects about the major ecosystems of the world provide extensive information about the interactions of living things all over the planet. Of particular interest for each investigation were the interactions and connections among the organisms in each system—the symbiotic relationships, parasitic dependencies, adaptations, and links in complex food chains—that characterize the cycles within the ecosystems. The students’ colorful and detailed posters highlight all of these details, while also presenting fascinating glimpses into many natural wonders.

Asian elephants trample down grasses and other plants as they traverse the rain forest. In scientific terms, Elephants are macro-fauna—large animals who inhabit a particular environment. The paths they carve make it possible for smaller animals to make their way through the dense vegetation of their habitat. Elephants also contribute to the reproduction of certain plants, whose seeds can only germinate after passing through the animals’ digestive tracts. The life-affirming presence of elephants is contrasted by the micro-fauna of the rainforest, such as yellow fever and malaria microbes, which are transmitted by infected mosquitos.

Multiplying inside the bodies of insects is only one method of survival for tiny organisms. In coral reefs, plankton process sunlight into energy for the living coral, and the coral provide a stable shelter for the vulnerable plankton. In the deciduous forest, fungi live on plants and exchange proteins that both organisms need. As the seventh graders have learned, this type of relationship is known as mutually trophic—both species benefit from their coexistence. The students also discovered and described less beneficial situations (such as the parasitic qualities of malaria), which favor one species over another. A major hazard for coral reefs comes in the form of an abiotic condition. When algae blooms block sunlight from penetrating the water, coral and plants cannot grow and the entire reef is at risk.

The 7th grade ecosystem posters explain specific and unique phenomena such as the adaptations of animals’ feet: the hooves of caribou in the tundra have evolved to be flat and wide like snowshoes to support an animal walking across vast expanses of snow. In a much warmer climate, the bottoms of the desert fennec fox’s paws are covered with hair to protect the animals from the heat of the sand. Trees and plants also figure prominently in the students’ research. In the coniferous forest, black spruces’ branches point down so that snow can slide off. In the savannah, plants have developed long roots that reach deep into the ground to tap moisture during the dry season. In the mountains, clover grows abundantly, providing nutrients for grazing mountain sheep. The herbivorous sheep derive energy from plants in an essential biotic form. If you were wondering about your own biotic relationships, the students who studied the grassland ecosystem have some encouraging news. The “breathing cycle” between plants and animals is still intact.