Developing Expertise for
Welcome! This page provides perspectives, general practices and links to resources for helping students to develop expertise for conducting self-directed experiments in science & technology. Experiments can be used for Judging Ideas, which is a major phase of my constructivism-informed pedagogical framework. If you have comments, questions, suggestions, resource ideas, etc. about anything here, please write to me about them. Thanks.
scientists & technologists seek empirical support for claims about
phenomena, they often use experimentation.
This is an approach that should be distinguished from 'studies,' about
which perspectives and practices are elaborated elsewhere. As indicated in the figure at
right, an experiment is an activity in which the one or more
independent ('cause') variables are forced
to change. To develop ideas about food decay, for example, we could
conduct and experiment by steadily increasing the temperature
(independent variable) of
food-bacteria mixtures and measure the rate of food decay (dependent
['result'] variable). Instead, we could find
some food-bacteria mixtures in nature, measure their temperatures and
determine the rate of decay in each case. This latter type of inquiry
would be a study, which is a type of inquiry in which the independent
('cause') variable is allowed to change naturally. It also would be a correlational study, because we
would be comparing (correlating) how changes in one
variable (e.g., natural temperature changes) may affect changes in
another variable (e.g., rate of decay).
|Which of these two sorts of investigations inquirers choose to use depends on various factors. Experiments often produce quick results and, for that reason, they may be preferred over studies. Sometimes, however, experimentation is impractical and, therefore, studies are necessary — as in the case of much of astronomy, for example. Perhaps more significantly, it often is ethically problematic to conduct experiments in some cases. With every experiment, there is a risk of negative side-effects of forcing a variable to change. Asking volunteers to smoke different numbers of cigarettes in order to determine cigarettes' effects on human heart rate may work, but it risks giving them lung cancer! — along with other possible unexpected negative side-effects. Such issues are elaborated below and through my page about studies.|
various approaches for helping students to develop skills they could
use for conducting experiments, but resources here are
based on the constructivism-based approach at Skills
Pedagogy. Resources for the Modelling & Practice stages of this
framework are provided on this page, through the links at right.
Resources for helping students to express their
pre-instructional skills for science inquiry (including
experimentation) are provided at Expressing
Teachers can engage students in discussions, in a Socratic
style, usually involving manipulation of concrete phenomena in an
experimental way. Four common techniques are illustrated below. During
and after such demonstrations, teachers should ensure students at least
begin to develop understandings of important principles relating to
example, those ideas described briefly at right.
|Ball & Ramp: This demonstration simulates a ski ramp or playground slide. The idea is to explain the set-up (shown at right), demonstrate what it can do, relate it to skiing or sliding, and get students to help you design a 'fair' test. Variables affecting distance travelled may be: angle of ramp, weight of ball, force of release of ball, diameter of tube, etc. Through trial-and-error and discussion, students generally can develop understandings of the sorts of points list above.||Elastic Band Launch: This
demonstration should only be chosen when working with students who have
the maturity to handle its 'fun' aspect. Again, show students how to
'launch' elastic bands and engage them in a discussion about what
test(s) can be conducted with them (perhaps using bands of different
lengths and thickness). As a WISE Problem application, you might
discuss these as rocket tests.
Seltzer: Alka Seltzer™ breaks down to produce
gas upon contacting water. The amount of gas formed tends to depend on
the water temperature, the acidity (increased by adding vinegar),
area of tablet (by breaking it into smaller pieces), among others.
to use a large cylinder (or clear, plastic bottle); One seltzer tablet
easily displaces more than 100 mL of water (The container of water is
in the tub by cupping a hand over its opening!). A possible WISE
Problem connection could be made by asking students to read the
ingredients list for the seltzer and research their effects.
There are several variations of using balloons for pointing out the
sorts of characteristics of experiments as those listed above. Balloons of
different sizes and shapes can be shown to students. The teacher can
ask students what can be done with them to learn more about them. They
suggest inflated them and letting them go. This lends itself to
looking at distance travelled, loops completed or sound made, etc. Or,
students might suggest tying the balloons off, inflating them to
different volumes and letting them drop. They also might suggest using
them to create static electrical charges in people's hair. Try to work
with some of the students' suggestions. Others can be reserved for
guided practice, below.
Reading: Teachers should encourage students,
depending on their
age and stage of development, to read various summaries and
descriptions of experimentation — such as
description @ Sample Experimental
Project. Many of these are available on various Web sites, accessed
through Skills Ed. Resources.
Many textbooks also provide information about the nature of
experimentation. All such resources should be used with caution, paying
attention to the extent to which they provide realistic portrayals of
experiments and their role in science and technology. The extent to
which they suggest that knowledge buiding is an inductive/empirical
process often is a problem, for example.
|Multimedia References: Students can learn about the nature of experimentation through films, video recordings and various animated Web pages on the internet. Teachers can check their school, school district and union libraries. Web-based resources are available through Skills Ed. Resources. Again, all such resources should be used with caution, paying attention to the extent to which they provide realistic portrayals of experiments and their role in science and technology. The extent to which they suggest that knowledge buiding is an inductive/empirical process often is a problem, for example.|
|Students should be given several opportunities to gain some practice in developing expertise regarding experimentation. Generally, these may involve: i) designing & conducting experimental inquiries and/or ii) analyzing & evaluating completed inquiries. As students work through the various activities, they should have opportunities to interact with peers. Teachers also should interact with students on a regular basis, questioning them about what they are doing and reasons for their actions. Generally, teacher interactions should encourage students to develop independent experitse, rather than developing a reliance on the teacher for the 'right' answers, methods, etc. Some specific suggestions for these sorts of activities are provided at right, along with links to relevant resources.||