The sloshing mix of chemicals in the school laboratory tray simulated a rat. By watching the color of the solution change through "feeding" various food additives and other chemicals to the "rat," the eighth-grade students determined that the rat had gotten sick, or had died, depending on the amount of chemical exposure.
They then mathematically extrapolated the rat simulation to what would happen to a human given various doses. In the process, they learned basic facts about safe exposures, short-term exposures, and levels of additives and toxics found throughout industrial society.
The laboratory exercise is part of a nationwide project being piloted in several San Diego County schools to show students that chemistry affects all aspects of living and is far more than a difficult academic discipline to be avoided if at all possible.
"Most people--not just students--think of chemicals as having to do with substance abuse or involving white-coated, fuzzy-haired scientists pouring test tubes back and forth," said Lars Helgeson, science coordinator for the San Diego County Office of Education.
"But reality is that chemicals surround all of us in whatever we do: aerosols, pesticides, herbicides, solvents, plus all the medicines that are available. Everything that exists has chemicals as their base."
The new program is designed to correct what science educators believe is a "chemically illiterate" society that fails to understand scientific concepts and the element of risk inevitable to its existence. Scientists at the UC Berkeley Lawrence Hall of Science drew up the curriculum over the last 3 1/2 years under a grant from the California Chemical Industry Council. Lawrence Hall scientists have developed several primary and secondary education science curricula over the last decade.
It's intended primarily for junior high students, to have them understand how science is directly related to issues in society," said Joe Davis, assistant director for the project at Lawrence Hall. "Junior high is the last chance to expose all students to hands-on activities that keep fundamental principles at concrete, operational levels. Not all students take science in high school and (that coursework) tends to be more abstract."
Three Area Schools
Three San Diego County schools--Vista High School, Gompers Secondary School in San Diego, and Olive Pierce Junior High in Ramona--are among several in California and across the United States using the first materials from Lawrence Hall. Various lessons are being periodically introduced in science classes.
"The program involves more than just (textbooks), which is good," Olive Pierce general science teacher Joe Smith said. "By having the kid actually do something, and not just listen to me and take notes, I think they will retain the information longer." In addition, the curriculum does not require extensive laboratory equipment--which many junior high schools lack in any case--but uses small kits with eye droppers and other inexpensive equipment.
Last week, Smith had his students perform dilution experiments so that they would understand the meaning of phrases such as "parts per million" that often appear in news accounts of pollution or exposures to toxic substances. Smith's class diluted red food coloring to the point where the color disappeared completely, giving the students an idea of the difficulty involved in detecting such trace amounts. In combination with the rat feeding simulation, the students learn the meaning of a lethal dose, defined as the point where 50% of test animals die.
"The kids find out that there are no easy answers to whether a substance is safe or harmful for human consumption at various levels of parts per million--or at times parts per billion," Davis of Lawrence Hall said. "They will come to understand that all measurements have uncertainties involved and that the limits imposed by various government agencies (on toxic materials) are educated guesses based on scientific experimental evidence, with a safety (margin) factored in.
"We want everyone to understand in a rational, logical way the advantages and disadvantages of using chemicals, to have students look at evidence and not have decisions based on feelings and attitudes."
That view might strike some people as pro-industry or anti-environment, especially since chemicals have so frequently been associated in the public mind with environmental harm.
But both Davis and Helgeson strongly deny that the program has any bias, despite the funding support from the chemical industry.
"We have had a free hand in presenting an unbiased point of view," Helgeson said. "They are not paying us to tell their side of the story but telling us to get the word out about how a modern society should interpret chemical uses."
Helgeson said the curriculum could be modified for presentation to adult groups as well.
"The real concern of industry and of scientists is that we have an informed public, so that people will know how to evaluate information, and know what is good and bad about toxic levels, and trash burning plants, and solvents dumped down drains."
Olive Pierce's Smith said that students are aware, in general terms, of environmental problems, such as contamination of groundwater in the Ramona area northeast of San Diego.
"But they don't know the terminology or the process" that a scientist uses in investigating such problems, Smith said. And that is where he finds the greatest benefits coming from the program. "The kids will be able to make decisions about how (society) should use chemicals in the future."