Don Rathjen says he has been teaching high school science
"since the crust cooled." When you press him, he admits to thirty years of teaching, including experience in both Liberia and Turkey,
where he learned the value of hands-on teaching using simple, available materials. Don, who was the teacher project director for the
Snackbook, has been working with other teachers at the Exploratorium since 1984 and was named Outstanding Teacher by the Exploratorium in
This simple demonstration, called "Disappearing Glass Rods," is one of Don's favorite Snacks. He leaves the beakers and rods and syrup lying around his classroom for months. The students who play with them get sucked into exploring and discovering science on their own.
When you enter Don's classroom, you may come face-to-face with a page-size Fresnel lens hanging from the ceiling (see the "Giant Lens" Snack, page 17). Don tells of students who duck under the lens for months, and then suddenly discover it. Don finds it essential to allow his students the time to discover things on their own.
When Don teaches optics, he uses the "Giant Lens" as a demonstration. By holding the lens at just the right distance in front of his face, his class sees his head replaced by a giant eye. (You can see this amusing effect on the back of this magazine.) The students laugh, but they want to try it too. When they come to Don with questions, he guides them in their personal investigation of image-making.
The page-magnifier lenses that Don uses are rugged, plastic Fresnel lenses available for less than two dollars each at discount stores. Two upside-down metal binder clips, resting on their flat bottoms, hold the lenses upright and in place on student's desks.
Don always has his eyes open for interesting science materials. He finds them at plastics stores, toy stores, even flea markets. A Fresnel lens that came from the back window of a delivery van looks just like the one Don has hanging in his class, but produces opposite visual effects. When Don holds it in front of his face, his head appears to shrink. The students love it.
Even if lenses are not a part of your curriculum, says Don, don't let that stop you from leaving them around for kids to experience. Don's classroom is filled with attention-getting materials: a gyroscope fashioned from a bicycle wheel; a pile of blocks used to demonstrate center of gravity; pendulums that swing in peculiar ways, and many, many more.
These attention-grabbers-whose construction is detailed in the Snackbook-motivate students. Try them yourself. You may be surprised at the discoveries both you and your students make.
Vivian Altmann is a teacher who works with students in a
non-traditional setting. As head of the Exploratorium Children's Outreach Program, she and her team go out into the neighborhoods-to the
Youth Guidance Center and the community centers of San Francisco-to bring the Exploratorium's style of hands-on science to at-risk and
After the usual introductions, Vivian divides the kids into teams. She gives each group a length of insulated wire, a paper cup, twenty cents worth of small magnets, two metal paper clips, a D-cell battery, and a rubber band.
The teams immediately initiate a friendly competition to see who can build the "best" motor. Soon, one team has its motor turning, then another team. The groups compare motors to see whose is fastest. When one group cannot get their motor to run, Viv gets the "experts" from another team to help. The kids decide to swap parts between motors: the problem turns out to be a dead battery! The motor construction is just fine, after all. The kids razz the Exploratorium team for bringing them a dead battery, and then turn back to their motors. The room is buzzing.
Without even noticing it, these kids are learning about electricity, magnetism, and motors. When the kids make guesses about what will make their motors run better, and then test them, they are doing science. Will twice as many magnets make the motor turn twice as fast? Vivian answers by giving the team more magnets. The motor turns faster, but not twice as fast. What about using two batteries? The questions and suggestions came thick and fast, and the kids get the satisfaction of making discoveries on their own. They're learning important techniques for answering questions and solving problems; they're working cooperatively, making new friends, showing off their skills, and succeeding in science.
Judith Christensen, 1989 recipient of the
Exploratorium's Outstanding Teacher Award, currently teaches five sophomore physics classes at Galileo High School in San Francisco. She
has taught preschool, elementary, middle school, and special-education classes and works with teachers at all levels to promote hands-on
science. Her class is noisy, messy, and exciting-a place where kids discover the mysteries of physics for themselves.
Judith organizes her class into six multi-ethnic groups of six students. Each group builds its own equipment, does a scientific investigation using that equipment, and then presents oral and written reports based on its explorations. The students also evaluate each other's work. This day, the class is building the "Electroscope" Snack (see page 15). Once the electroscopes have been constructed, the students will use them to investigate electrostatics.
For this laboratory, all of the teams have successfully built electroscopes by draping charged strips of Scotch Brand Magic Tape(r) over bent soda straws stuck into film cans full of clay. Judith found the tape in administrative supplies; the straws were donated by a local fast-food restaurant; the film cans came from a neighborhood camera store, and the clay came from Judith's own collection of supplies. The resulting electroscopes are not black boxes made by some science supply house; there are no hidden or mysterious parts. The students have built them, and so "own" them. If an electroscope breaks, the students fix it or build a new one.
Each group checks the electroscope it has built. One girl combs her hair and brings the plastic comb toward the strips of tape dangling from the soda straws. One piece of tape is repelled by the comb, but the other is attracted. The electroscope works! The team cheers and brags to the surrounding tables. They call Judith to come see their work. She lets them give her the complete demonstration, then reminds them of the importance of writing down what they see.
To build the exhibits, each team draws
on the talents of all its members. Some students are better at figuring out how to build equipment from the illustrations and photos,
some are better at reading, others are better at making things work. If you listen carefully, you'll hear discussions in Cantonese,
Vietnamese, and Spanish, but English is the lingua franca of this classroom. Students who are better at English become language teachers
for the others in their laboratory group. Students who are better at science become science teachers, even if they are just learning
English. The final result is a team effort.
In addition to science and English, students in this classroom are learning about different cultures. Judith finds that when students from different backgrounds work together, they become more understanding of each other. As a spur to participation, she requires that the groups give each member a group cooperation grade.
There is a commotion over at one of the tables. Rather than attracting one piece of tape and repelling the other, a comb has attracted both pieces of tape. With Judith's guidance, the students test their comb on another team's electroscope. When it attracts both tapes of that electroscope as well, they realize that the comb is the problem. When they try another comb, they realize that the first comb wasn't charged. Their electroscope works just fine. But Judith doesn't let the matter stop there. She asks her students to write down what they saw and did. Judith can then guide them as they delve further into the behavior of electrical charges.
Judith doesn't have all the answers for her student's questions, but she admits when she doesn't know them and encourages her students
to help her find the answers. Year after year, she and her students learn more about science. And each year, the students guide Judith
toward becoming more comfortable and adept at helping them to find their own answers.