>> Publications 1994-1996

Aim

According to the teaching guidance for science of the new high school curriculum to be revised in 1994, teachers are strongly demanded to actively research and develop teaching materials and by gathering audio and visual materials and performing interesting experiments to aid students to deepen their interest and understanding in science.

However, I, as a science teacher, am disappointed with the present situation of the students' low interest in science which is caused by too much audio and visual information and becoming too familiar to them that they have lost their desire to try what they have seen and heard by themselves.

On the other hand, the teachers have lapsed into the tendency to teach science for the sake of passing entrance examinations and therefore to emphasize theory and calculations, so that classes are done with paper and pencil and with few experiments to back up the theories. In this way, the teachers are responsible for the lack in expansion in science classes.

This research was inspired by a girl student whom I saw take home a filter paper used in an experiment as if it was something valuable. This gave me the idea of a "take home experiment work" as you would take home pieces of work of art or home economics.

Instead of pouring experiment results down the drain when the experiment is over, my idea is to keep the students' results on filter paper, so that each student can preserve their experiment results and in so doing sustain their enthusiasm in learning science.

Outline

1. Dissolve more than two chemicals in water and spot a small amount onto filter paper using a capillary and cause various chemical reactions to occur in the centre of the filter paper. (Photos 9-1P to 3P).

In this way, each student is able to take their time in observing the capillarity change before and after a reaction, which would not be possible with a test tube.
2. In the case of inorganic chemical reactions, various reactions of solubility, ionic reaction, precipitation, neutralization, oxidation-reduction reaction of compounds, group reaction of metallic ions and metal complex can be confirmed by experimenting on filter paper.

3. As for organic chemical reactions, colour reaction for confirming functional group is suited for this method, as well as confirmation of carboxyl group and carbonyl group, or separation of various amino acids, synthesis of dyestuff, separation and confirmation of natural compounds and the like.

4. We cannot only do qualitative analysis of chemical change by colour reaction but also by confirming the shades of colours of various concentration of solutions, we may conduct a semi-quantitative analysis. We can make a concentration chart by colour reactions of such inorganic ions as copper, iron, chrome and manganese ions, and in so doing can confirm the concentration of waste fluids without using the costly litmus paper.

5. This method is not only effective for confirming chemical change by colour reaction but also for confirming compounds by smell. Particularly, for confirming the relationship with smell of functional group of organic compounds, isomer and molecular weight, I named such method of analysing substances by smell "hanalysis" (hana=nose + analysis), which delighted the students very much. (Photo 9-4P).

6. Experiment of burning organic compounds absorbed in a swab and estimating the content amount of carbon from the state during combustion also interested the students very much. (Photos 9-5P to 7P).

7. By this method, students can confirm by just smelling the tip of the swab the appearance of soot, the smell before burning and after in the oxidized state, the smell of the oxidized compound, etc.

Method of Making Teaching Material

1. Filter paper for use in Experiment

The filter paper used here is the round filter paper commonly used in students' experiments. On it, the students will each draw lines with crayons or oil-based ink as shown in photos 9-8P & 9P using a scale in sizes suitable for each experiment. This is in order to prevent chemical reactions from occurring among the different solutions tested on the paper. Therefore, for aqueous chemicals we will use oil-based ink or crayon but for oil-based chemicals, especially for nonpolar organic compounds, we must draw the lines with water-based ink or else they may be printed.

If square filter paper used for paper chromatography (40 x 40cm) can be obtained, it would be possible to raise the efficiency of experiments by printing the contents as in photos 9-12P to 16P which will unify the style. Instructions may also be printed.

If instructions of experiment conditions and comments are printed, this should greatly help the students especially for complicated reactions.

Also, if filter paper for chromatography (2 x 40cm) available at stores can be used, many spots may be taken so that a standard colour chart is made for comparing colours of several concentrations of solutions for semi-quantitative analysis, or by spotting with swab various acid salt radicals onto various pH indicators prespotted onto each area.

2. Swab for use in Experiment

Initially, I tried to spot solutions onto filter paper using a glass capillary and hoped that by capillarity solutions A and B would react in the centre of the filter paper.

However, the size of the spots differed from capillary to capillary and depending on the students using them. There was also fear of capillaries breaking during the experiment which might injure the students' hands. I therefore thought to substitute swab for capillary.

With swabs, the sizes of the spots became uniform, there was less failure, and with swabs in both ends, one may absorb solutions A and B on each end of one swab which is very convenient. We are also able to get fashionable swabs of which the plastic axis come in various different colours. This is useful for sorting out the various types of compounds.

Recently, there are also types of swab that have earpick on one end. This is very convenient for experiments in which it is necessary to spoon a uniform amount of powder.

Guidance Method

This method of chemistry experiments using filter paper instead of test tubes enables students to confirm by observation the state before and after a reaction of inorganic chemical reactions as well as organic chemical reactions by intentionally selecting chemicals that change colour when undergoing chemical reaction.

Moreover, by making use of the different shades produced in colour reactions of chemical change, it is possible to teach chemistry in a semi-quantitative way as well as in the qualitative sense.

For those reactions that need heating or cooling, if it is up to 200oC the reaction may be done by placing the filter paper on a heating plate or iron.

To cool, we may place a sheet glass or aluminum foil over an instant refrigerant or ice, and set filter paper on top for reaction.

If we want to regulate the temperature, as filter paper will reach the desired temperature instantly, wrapping a filter paper around a beaker filled with water of the right temperature will do the trick.

In reaction with gas, we may first absorb the solution onto the filter paper and then hold the gas up to the paper to let them react.

As reaction occurs much faster with filter paper than with test tubes, it is convenient to use this fact to teach students that in the natural world the oxidized state is the most stable form. However, if oxidization is to be prevented, we may seal the reacted spot with cellophane tape and preserve the state permanently.

Effectiveness upon actual practice

1. Students had tendency to avoid chemistry experiments because of the 3Ks, i.e. "kowai" (frightening), "kusai" (bad smell) and "kitanai" (dirty) but this method of experimenting has helped get rid of that attitude. The students began to challenge "bad smells" and eagerly took home experiment results to show their parents.

2. Chemistry experiments are conducted by "observing, listening and recording". One should observe well, listen attentively to the teacher's explanation and instructions, and record what one has seen and heard. The students were motivated to do all these things.

3. The gap in the interest towards chemistry experiment between girls and boys shrank. Where there was a subconscious fear towards the danger and harmful effects of chemicals, this method of reacting chemicals on filter paper use an extremely small amount so that, feeling safer, each student can without aid conduct their own experiment. All the students will be able to clear up the experiment together too so the feeling of unfairness is gone.

4. As the reaction is done on filter paper, the experiment is over at once, so it is possible to increase the items of experiment. In the past, much time and expense was necessary to dispose of the waste fluid in test tubes but this has become unnecessary. A great amount of chemicals is also saved.

5. The experiment became the "works" of each student and could be taken back to their classrooms. Therefore, the experiment could be re-enacted in class which helped expand the contents of the class.

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