College Board Statement Concerning Labs
Laboratory experience must be part of the education of AP Physics students and should be included in all AP Physics courses, just as it is in introductory college physics courses.
In textbooks and problems, most attention is paid to idealized situations such as:
Ø ffriction is often assumed to be constant or absent;
Ø meters read true values;
Ø heat insulators are perfect;
Ø gases follow the ideal gas equation.
It is in the laboratory that the validity of these assumptions can be questioned, because there the student meets nature as it is rather than in idealized form. Consequently, AP students should be able to:
Ø design experiments;
Ø observe and measure real phenomena;
Ø organize, display, and critically analyze data;
Ø analyze sources of error and determine uncertainties in measurement;
Ø draw inferences from observations and data; and
Ø communicate results, including suggested ways to improve experiments and proposed questions for further study.
Laboratory experience is also important in helping students understand the topics being considered. Thus it is valuable to ask students to write informally about what they have done, observed, and concluded, as well as for them to keep well-organized laboratory notebooks.
Students need to be proficient in problem solving and in the application of fundamental principles to a wide variety of situations. Problem-solving ability can be fostered by investigations that are somewhat nonspecific. Such investigations are often more interesting and valuable than “cookbook” experiments that merely investigate a well-established relationship and can take important time away from the rest of the course.
Lab related skills, such as design of experiments, data analysis, and error analysis, and may distinguish between students who have had laboratory experience and those who have not. In addition, understanding gained in the laboratory may improve students’ test performance overall.
Implementation and Recommendations
Laboratory programs in both college courses and AP courses differ widely, and there is no clear evidence that any one approach is necessarily best. This diversity of approaches should be encouraging to the high school teacher of an AP course. The success of a given program depends strongly on the interests and enthusiasm of the teacher and on the general ability and motivation of the students involved.
Although programs differ, the AP Physics Development Committee has made some recommendations in regard to school resources and scheduling.
Since an AP course is a college course, the equipment and time allotted to laboratories should be similar to that in a college course. Therefore, school administrators should realize the implications, in both cost and time, of incorporating serious laboratories into their program. Schools must ensure that students have access to scientific equipment and all materials necessary to conduct hands-on, college-level physics laboratory investigations as outlined in the teacher’s course syllabus.
In addition to equipment commonly included in college labs, students in AP Physics should have adequate and timely access to computers that are connected to the Internet and its many online resources. Students should also have access to computers with appropriate sensing devices and software for use in gathering, graphing, and analyzing laboratory data and writing reports. Although using computers in this way is a useful activity and is encouraged, some initial experience with gathering, graphing, and manipulating data by hand is also important so that students attain a better feel for the physical realities involved in the experiments. And it should be emphasized that simulating an experiment on a computer cannot adequately replace the actual, hands-on experience of doing an experiment.
Flexible or modular scheduling is best in order to meet the time requirements identified in the course outline. Some schools are able to assign daily double periods so that laboratory and quantitative problem-solving skills may be fully developed. A weekly extended or double laboratory period is recommended for labs. It is not advisable to attempt to complete high-quality AP laboratory work entirely within standard 45- to 50-minute periods.
If AP Physics is taught as a second-year physics course, the AP labs should build on and extend the lab experiences of the first year course. The important criterion is that students completing an AP Physics course must have had laboratory experiences that are roughly equivalent to those in a comparable introductory college course. Past surveys of introductory college physics courses, both non calculus and calculus-based, have revealed that on average about 20 percent of the total course credit awarded can be attributed to lab performance; from two to three hours per week are typically devoted to laboratory activities. Secondary schools may have difficulty scheduling this much weekly time for lab.
However, the college academic year typically contains fewer weeks than the secondary school year, so AP teachers may be able to schedule a few more lab periods during the year than can colleges.
Also, college faculty have reported that some lab time occasionally may be used for other purposes. Nevertheless, in order for AP students to have sufficient time for lab, at least one double or extended period per week is recommended for all AP Physics courses.
Laboratory activities in colleges and AP courses can involve different levels of student involvement. They can generally be classified as:
Ø prescribed or “cookbook,”
Ø limited investigations with some direction provided, and
Ø open investigations with little or no direction provided.
While many college professors believe that labs in the latter two categories have more value to students, they report often being limited in their ability to institute them by large class sizes and other factors. In this respect, AP teachers often have an advantage in being able to offer more open-ended labs to their students.
In past surveys, colleges have cited use of the following techniques to assess student lab performance:
Ø lab reports, direct observation,
Ø written tests designed specifically for lab,
Ø lab-related questions on regular lecture tests,
Ø lab practical exams, and
Ø maintenance of lab notebooks.
Note: I will use all of these techniques
When the colleges assessed laboratory skills with written test questions, they reported attempting to assess the following skills in order of decreasing frequency:
Ø analysis of data,
Ø analysis of errors,
Ø design of experiments
Ø evaluation of experiments
Ø suggestions for future investigations.
Documenting Laboratory Experience
The laboratory is important for both AP and college students. Students who have had laboratory experience in high school will be in a better position to validate their AP courses as equivalent to the corresponding college courses and to undertake the laboratory work in more advanced courses with greater confidence.
Most college placement policies assume that students have had laboratory experience, and students should be prepared to show evidence of their laboratory work in case the college asks for it. Such experience should be documented for the AP course by keeping a lab notebook or a portfolio of lab reports. Students should be encouraged to keep copies of this work and any other work from previous lab experience. Presenting evidence of adequate college-level laboratory experience to the colleges they attend, as an adjunct to their AP grades, can be very useful to students if they desire credit for or exemption from an introductory college course that includes a laboratory.
Although colleges can expect that most entering AP students have been exposed to many of the same laboratory experiments performed by their own introductory students, individual consultation with students is often used to help determine the nature of their laboratory experience.