In my three years as a high school chemistry teacher, I have heard the “I hate science” comment more times than I would like to count. Thus I was delighted to hear two students discussing how much they enjoyed the first activity of the school year. In their words, this was the first time they had ever gotten to actually do science—as opposed to listening to the teacher talk. What astounding and intellectually stimulating activity could have prompted such a change in attitude?
I used a simple, yet visually impressive procedure. Following my instructions, students placed whole milk in a petri dish, then added single drops of various food colorings along the perimeter. Students then added a drop of dishwashing detergent to the center of the dish. The colors began to swirl and move until they all blended together. I reminded my students to take detailed notes as they observed the reaction.
They began to ask questions almost immediately. Why did the colors move? Would this work in other liquids? How long will the reaction continue? We listed the questions on the chalkboard. Questions that called for more than a simple yes or no were separated from the others.
The students divided into groups, with each group selecting at least two questions. They then spent the next two days designing and executing experiments to determine why the reaction occurred. Once members of each group determined their methodology, they submitted to me a list of materials they would need for their experiments.
As a former student of Anton Lawson, Professor of Zoology at Arizona State University, I have incorporated his philosophy of teaching science into my chemistry curriculum. Lawson uses disequilibrium as a basis for teaching—students are challenged by phenomena that cause them to question ideas and beliefs they previously held. They then develop possible explanations for these phenomena, and design methods to test their hypotheses.
Until they collect the data, all hypotheses are considered valid. Only after collecting and analyzing the data do the students draw conclusions about whether or not they have supported their ideas scientifically (Lawson 1995). Even then, however, no hypothesis can be proven false; some ideas simply cannot be tested in the classroom.
This approach benefits students in three ways:
- They learn to appreciate the nature of scientific methodology.
- They become actively engaged in scientific inquiry.
- They gain confidence in their ability to become independent problem solvers.
Students improve their independent thinking quite rapidly when their questions are met with questions. In my classes, I try to ask the types of probing questions that lead students to discover the answers on their own, instead of giving them answers immediately.
Concepts Are Key
The investigation with milk and food coloring is an excellent example of a Discovery Learning activity. Students did not develop a complex chemical explanation for their results. In fact, even experienced chemists do not completely understand the precise reasons for the swirling colors. My novice chemists were able to reach the following conclusions:
- The type of milk affected the amount of reaction.
- Orange juice, water, and egg whites did not cause a reaction.
- Temperature had an effect on how fast the reaction occurred.
- The milk swirled when detergent was added, even if no food coloring was added.
- Liquid soap, granular detergent, and other cleansers caused a reaction.
From these data, they determined that the reaction seemed to be caused by some substances in soap that reacted with some substance (probably fat) in the milk. The actual mechanism, though not completely understood, involves polar and nonpolar ends of soap molecules. The nonpolar end is attracted to the fat in the milk, which starts the swirling when the detergent is added.
In another experiment, students studied gas laws by designing, constructing, and launching their own hot-air balloons. As they made modifications to get their creations airborne, they saw in dramatic fashion how temperature, mass, and volume affect balloon flights.
The activity-based teaching that uses Discovery Learning follows the standards developed by the National Research Council's Committee on Science Education Standards Assessment (1994). The standards suggest
- limiting the amount of content;
- covering important concepts in depth; and
- extensive use of hands-on activities that promote critical thinking skills.
In Discovery Learning, concept development is more important than content overload, and thinking is considered more productive than memorization. The time needed to fully develop and test hypotheses necessarily limits the amount of content teachers can cover. But students can more fully understand and more easily apply the concepts because of the connections made when multiple areas of the brain are stimulated.
Learning in Context
Learning does not occur in a vacuum. The brain constantly searches for patterns and attempts to categorize information into relevant chunks of information. It matches, compares, and patterns incoming information after information already stored in memory. This is done at both the conscious and subconscious levels. The more meaningful, relevant, and complex the sensory input is, the more actively the brain will attempt to integrate and develop patterns (Hart 1983, Caine and Caine 1991).
Discovery Learning provides the complex and relevant stimuli necessary to allow learning to occur more easily. By manipulating materials, exploring possibilities, and seeing the outcomes of their investigations, students can form the connections between previous learning and new information.
According to Lawson, they also will develop a conceptual overview of a phenomenon, so that they more easily retain the vocabulary and small bits of factual knowledge necessary to complete the learning. And because of the contextual patterns developed through the discovery process, they will more easily remember words and phrases that previously were meaningless to them (Lawson 1995).
The initial reaction to these types of activities is often less than enthusiastic. Most students, in fact, are quite uncomfortable with this nondirected approach. They ask questions almost continually and want confirmation of their ideas at every step.
Students become frustrated for two reasons. They don't trust their own ability to be right, and they want to know if they are right before doing the testing.
Many students prefer the old, comfortable way of learning. They expect the teacher to give them all the information they need to know to pass the next test, which they may or may not memorize for the occasion. In Discovery Learning, however, the role of the teacher becomes less a keeper of knowledge than a facilitator in helping them to explore and discover the possible answers to a question.
Resistance to this approach may lead teachers to abandon it after the first few encounters. This is a mistake. By the second month of school, my students looked forward to investigations every few days. Several students wrote of their experience:
It helps me think more freely and independently.
These types of activities can help me in other classes by helping to develop thinking skills.
When we carry out our own procedures and draw our own conclusions, we learn how to move from one step to another—that if something doesn't work, we can go back and change it.
As students move to this level of independence, I feel as excited as they do about their ability to solve problems on their own and to apply what they have learned in their investigations to other situations. And they will ask: “When do we get to do another lab?”
Caine, G., and R. N. Caine. (1991). Making Connections: Teaching and the Human Brain. Alexandria, Va.: Association for Supervision and Curriculum Development.
Hart, L. (1983). Human Brain, Human Learning. New York: Longman.
Lawson, A. E. (1995). Science Teaching and the Development of Thinking. Belmont, Calif.: Wadsworth Publishing Co.
National Committee on Science Education Standards. (November 1994). National Science Education Standards, draft copy. Washington, D.C.: National Research Council.
Susan Skolnik begins teaching at St. Mary's High School this fall. She formerly taught at Tolleson Union High School. She can be reached at 4501 West Desert Hills Dr., Glendale, AZ 85304.