Chemistry Reference
In-Depth Information
Table 5.4
Some types of experimentation in classes
- Teacher demonstration
- Real experiment
- Student demonstration
- Thought experiment
- Student experiment
- Experiment demonstrated with media
- Division of work
- Qualitatively, quantitatively
- Simultaneous work
- Differentiation by amount of substance:
- Independent work
- Macroscale
- Halfmicroscale
- Microscale
Especially the
overhead projector
is a good way to intensify the planned effect
by projection and enlargement, for example, of glass dishes with colored indicator
solutions and their reactions with acids or bases. Also the bright light of the
projector is useful: by adjusting the mirror, the apparatus on the table can be directly
illuminated with the light or only the part of the apparatus, which shows the effect
(see also Chap. 4). If a
video camera
or a swan's neck camera is available, it is also
possible to enlarge effects that are hardly observable from the distance. This
method of experimentation gets by with small amounts of chemicals: “chemistry
en miniature” [
19
]. H
ausler's semimicro method [
20
] and Kometz's method of
cuvettes [
21
] also make it possible to run experiments with small amounts of
substances and mostly without the use of a hood.
Organization of lab classes:
The preparation of lab classes in chemistry is often
not limited to a single hour, most of the times a series of experiments of one
teaching unit has to be spread over several hours.
Experiments have to be tested in advance, transparencies for the overhead
projector or work sheets for student experiments have to be prepared and copied
for the lesson. The individual steps can be structured in the following way:
Preparation
(well in advance):
€
- Testing the planned student experiment
- Designing a work sheet for the student experiment
- Designing a power-point presentation
- Preparing chemicals and equipment
- Testing the planned demonstration experiment
- Drawing an overhead transparency of the apparatus
- Preparing the safety features
Procedure
(during lecture):
- Presenting the problem of the lecture
- Listening to students questions and discussion
- Explaining the assembly of equipment or apparatus
- Drawing the apparatus on blackboard or transparency
- Giving time to students to copy the drawings
- Explaining the safety features
- Conducting the experiment
