"Hands On" Discovery Learning
Discovery learning, a technique where students explore and deduce things for themselves is in vogue. Some administrators urge teachers to use these types of “hands on” activities as the dominant mode of instruction over written assignments and drills. In reality, discovery of things is a lengthy, random process! Placing inordinate confidence in problem-based exercises over teacher directed activities is misguided.
Open Ended Questions
Students working on “open ended” problems rarely figure out all the things they need to learn. For this kind of learning to be effective, a teacher must skillfully guide it. Given that these activities are often assigned to small student groups, the level of supervision necessary is untenable.
Although manipulatives may be appropriate for specific lessons, teachers are best equipped to decide which, if any, occasions to use a guided discovery process. Explicit instruction, using concrete examples and analogies to illustrate abstract concepts is the most effective instructional technique, given the limits of class time.
Using appropriate Examples and analogies to Teach Living Environment
As a staunch practitioner of direct instructional methods, I am always searching for appropriate examples (and useful analogies) of biological phenomena related to the Living Environment course. Throughout my years in the classroom I have used the oft cited:
Keeping Students Engaged
Keeping class presentations lively, with succinct information, student questioning, and vivid examples can be even more engaging than an activity with manipulatives. Once a unit is prepared, a teacher may wish to tweak or embellish certain points, but major amounts of time are not required. Contrast this to the preparation necessary where manipulatives are consumable and need to be replaced or need to be managed before use by another class.
How Hummingbird Characteristics Can Explain Different Science Topics.
With this post, I will describe how one tiny organism can elucidate several important science concepts. I invite instructors to include any or all of the examples I provide in their Teacher Toolbox of instructional ideas. The diminutive hummingbird is a worthy exemplar that can be used for several abstract concepts commonly taught by science teachers of middle, secondary, and undergraduate students.
Coevolution: The hand in glove match of narrowly shaped, nectar-bearing flowers to slender nectar-sipping hummingbird beaks is evidence that hummingbirds were shaped by co-evolution. Between 75% and 95% of flowering plants need reliable pollinators. That is 180,000 different plant species. Some of those plants evolved to produce flowers with a shape that demanded a long, slender bill. Hummingbirds’ evolution filled that niche.
In your classroom, show students examples of examples of flowers that are and are not pollinated by hummingbirds. This could be elaborated by including bees, bats, and other pollinators, for comparison purposes.
Survival of the Fittest & Sexual Selection: Even the smallest hummingbirds can be quite aggressive against much larger birds. Their extraordinary mobility allows hummingbirds to successfully chase away potential predators like hawks and crows. Hummingbirds are also aggressive against other hummingbirds! This can result in frequent fights over good feeding territories.
Evolution has acted not only to make flower and beak shapes complimentary, but also to make some hummingbird beaks weapon-like. The swordbill hummingbird (Ensifera ensifera) has a beak as long as its body and tail, (about 4 in (10 cm)). This beak is uniquely adapted to extracting nectar from the base of long, tubular flowers, such as the passionflower (Passiflora mixta).
Not only does the male Ensifera ensifera use its bill to feed, it also uses it to aggressively chase away others that want to feed in its territory. During their competition for resources, two males look like they are fencing. They stab and charge, pinch, pluck, and rip out feathers, fighting beak-to-beak, until one male ensifera tosses the other aside.
All hummingbirds fight, but the tooth-billed (Androdon aequatorialis) male hummingbirds’ beaks are thicker, more rigid, and hooked at the end. Sometimes they have jagged points similar to rows of teeth. These weaponized bills are less efficient at feeding, but this does not matter because the weaponized bill allows the males to control access to the flowers. They do not let anyone else near the nectar.
The weaponized adaptations of E. ensifera and A. aequatorialis make those hummers more fit for their environments. Like the antlers of deer or the girth of elephant seals, E. ensifera and A. aequatorialis use their beaks to fight off rivals for mates. This is sexual selection, where the improvement of mating chances is the dominant force determining which members of the species can pass their genes on.
Respiration and Nutrition: Hummingbird metabolism is a marvel of evolutionary engineering. These tiny birds can power all of their energetic hovering flight by burning the sugar contained in the floral nectar of their diet.
They are equally adept at burning both glucose and fructose, which are the individual components of sugar; a unique trait other vertebrates cannot achieve. Mammals, such as humans, cannot rely on fructose to power their exercise metabolism.
Hummingbirds have an optimal fuel-use strategy that powers their high-energy lifestyle, maximizes fat storage, and minimizes unnecessary weight gain all at the same time. Hummingbirds require an incredible amount of energy to flap their wings 50 times or more per second in order to maintain hovering flight. They are able to accomplish this by burning only the most recently ingested sugar in their muscles while avoiding the energetic tax of first converting sugar into fat.
While humans evolved, over time, to a complex diet; hummingbirds evolved on a diet rich in sugar. Hummingbirds are able to move sugar from their blood to their muscles at very fast rates.
While every cell in the human body can use glucose, the liver is the only organ that can metabolize fructose in significant amounts. When people eat a diet that is high in calories and high in fructose, the liver gets overloaded and starts turning the fructose into fat. The prevalence of high fructose corn syrup found in products like soda is also strongly linked to a rise in obesity rates.
Hummingbirds burn sugar so fast, that if they were the size of an average person, they would need to drink more than one can of high-fructose corn syrup soda every minute. If scientists can gain insights on how hummingbirds cope with an extreme diet then maybe it can shed some light on what goes wrong in us when we have too much fructose in our diet.
Aerodynamics – Physics Hummingbirds also offer opportunities to explore the limits of physiology. They have the highest metabolic rate among vertebrates, and they specialize in hovering, the most expensive form of locomotion in nature. Hovering is a form of flight that is of intense interest to the designers of flying robots. Scientists are interested in replicating hummingbird flight.
Scientific Inquiry- Hummingbirds can also be good research subjects. They will fly readily to feeders. The presence of humans does not put them off. Hummingbirds also fly really well in wind tunnels and cages.
Hummingbirds have been shown to be excellent learners. There is speculation that, because they live on the edge in terms of their energy budget, they may require a great memory for where the food sources are.
What are your thoughts?
Please let me know how you used any of these hummingbird examples with your students. If you have your own ideas for examples and/or analogies that have worked in your classroom, please share those, as well!
Also, you'll be able to learn more about hummingbirds with my new upcoming Young Adult Picture Book, which can be enjoyed by middle and teen readers, parents, and teachers. In it, flowers and their coevolutionary partners, insects, chat and do their jobs, producing and transporting pollen. They are quite preoccupied, In fact, it takes them a while to realize that many products have gone missing from their peaceful meadow environment. The northeastern meadow dwellers in the story make observations and collect evidence to identify the sneaky thief in their midst. Themes such as plant needs, coevolution, pollination, and ecology run throughout the story. Stay Tuned for the release of A Thief in Pollinator Paradise!
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Gertrude Katz has spent over 30 years teaching K-12 public school students all major subjects. She has taught biology and education at the college level. The majority of her career has been spent instructing biology at the secondary level.