Traditionally instructors use experiments in physical science instruction:
In both cases the instructor gives a lot of verbal and/or written guidance.
Research has shown that such use of experiments has been ineffective in helping acquire conceptual understanding or experimental skills.
Often students tend to learn physics as a group of disjointed concepts. They tend to accept scientific knowledge a "facts" without attempting to understand how it was constructed. But in every case in science, a person or people "invented" the laws as we know them though a complicated non-linear process. Very often students do not understand and are not encouraged to understand the coherent structure which underlies physics. We believe that it is the lack of this understanding which makes physical science traditionally "difficult" and decreases the level of confidence of the students.
If we look at scientific discovery through an historical lens, we can divide experiments into three broad categories. These are observational experiments (model/theory building experiments), testing experiments (model/theory testing experiments), or application experiments (application of the model/theory). These three categories of experiments joined together to construct a coherent scientific theory. The cycle may be summarized as follows:
The process can be summarized in the following diagram. Note that the cycle works for both qualitative and quantitative reasoning
In the spirit of a "cognitive apprenticeship" students learn the processes of science rather than the results. And the processes are learned by participation in them, ie: by observing and modelling the thought processes of an expert physicist, and by doing. Areas of physics are divided up into conceptual modules. Each module begins with one or more observational experiments. Little explanation is given, but scaffolding is provided to guide students through the technical details of making useful observations. Students examine the data, looking for patterns and relations between the physical quantities. The then construct a rule which models these patterns.
The observations and modelling will be followed by one or more testing/application experiments. Students either use their model to make a prediction and then devise an experiment to test the prediction, or they are given a challenge which requires them to use their model to predict an outcome of a specific experiment. If things do not work out as planned, students have to go back and revise their model, the assumptions made, the accuracy of any calculations and so on.
In the testing/application stage, the following reasoning scheme can be observed and practiced so that students acquire the skills of what is called "hypothetico-deductive reasoning".
Explanation/rule/idea is reasonable
AND we assume...
Hypothesis or proposed model
We do x
Suggested testing experiment
We would expect y to happen
Prediction based on explanation/rule/idea + additional assumptions about the system
Expected outcome occurred
Expected outcome did NOT occur
Explanation/rule/idea has not yet been disproven
EITHER: We made a mistake with our assumptions etc... OR Explanation/rule/idea is not valid in this regime
In following this process through, students are engaging in a process of mental modelling, constructing their own knowledge of physics in the same way as physicists do it. Not only do they understand the physics they are doing, but they are equipped with learning skills useful in any branch of science.
The web page provides examples of experiments that can be used in class or for homework for the students to observe physical phenomena, collect data, analyze data, build models and test their predictions. Students should not make any predictions before viewing observational experiments, the purpose of these experiments is to help students accumulate enough experimental data to make predictions based on some knowledge. Prediction experiments require predictions based on the explanations (models) that students proposed to explain the observational experiments. It is better to elicit several alternative models and then view the experiment. See example of a prediction .
The write-ups and videos are provided in a logical sequence. It is sometimes helpful to download the videos and analyze them through quicktime itself rather than through the web page since the videos can be enlarged and examined at greater detail. Each video clip can be viewed in real time if a viewer presses the "play" button and in slow motion, frame by frame, if the viewer presses the cursor keys once per each frame. Click for an example. Each clip is digitized at a different number of frames per second, please notice for each clip how many fps were used. There are no built in measuring instruments in the clips. The viewer has to make a conscious decision on what she/he wants to measure. The viewer must decide how to collect data, how to store it and how it should be analyzed. Example . Data analysis can be done using Excel. Position data can be collected using the rulers in the videos or using transperency paper attached to the computer screen.