Instructional principle: Knowledge is often hierarchical, and frequently the best way to assure performance on higher-level objectives is to identify the prerequisite skills needed for a current unit of instruction and ascertain that students have mastered them.
If the teacher performs a task analysis to determine what skills students must be able to perform before learning a more complex skill and then verifies that the students already possess all these prerequisites, the students will almost always master the new ability quickly and easily. The main reason students have trouble with new skills is because they lack the prerequisite skills. This principle applies to all subjects teachers cover in their classrooms, including concepts, principles, intellectual skills, and physical skills.
When learning is ineffective, it is often because a task analysis or pre-assessment of skills has not been conducted. If the pre-assessment shows that some of the students are lacking some of the prerequisite skills, these should be taught before moving to the targeted skill. Of course, if students not only lack prerequisite skills but also have misconceptions, then the need for correction is even more serious. The value of organizing instruction hierarchically and ascertaining that students have mastered prerequisite skills is discussed in detail in Gagne (1985).
In spite of the obvious value of assessing and teaching prerequisite skills, such preassessment is actually relatively rare. This is because
The computer can help by compiling and disseminating a database of task analyses and prerequisite skills, by performing the assessment, by delivering the remediation, or by doing all of these activities.
Programs that diagnose prerequisite skills are fairly recent. Seven of the disks in MECC's Mastering Math (Get a new one!) series cover specific mathematics skills. The other three disks integrate the other seven. One of these provides a series of diagnostic tests to determine what skills the students possessed or lacked. A second supplies a management system to guide the students in running appropriate programs and to keep records on their performance. The third disk generates worksheets for students to complete as homework or seatwork. Several other companies are moving in the same direction.
Another example of effective computerized diagnosis is shown in Figure 3.10. ADD NEWER EXAMPLES. This program presents students with scientific problems to solve. It records not only the answers that students give, but also the types of thinking in which they engaged while solving the problems and the types of mistakes they made. Teachers can later access the results to determine what their students currently know about scientific problem solving.
Even without computerized diagnosis, the computer can make a valuable contribution by helping students develop prerequisite skills before beginning units of instruction. Prior to teaching a unit that requires measurement as part of a scientific investigation, for example, a teacher could make available the Math for Science ADD NEWER EXAMPLES program described in the "Direct Instruction" section of this chapter. Teachers are often aware that their students lack prerequisites, but they just do not have time to work with students who were supposed to have mastered these skills in a previous unit or in a previous course. Computer programs can help solve this problem by providing individualized remediation for subskills as necessary.
A further impediment to teaching prerequisite skills is that it is time-consuming for individual teachers to perform the task analyses needed to identify them. It is possible, however, to develop computerized databases FIND ONE AND REPHRASE THIS that perform task analyses for any topic covered in the curriculum. When a student encounters difficulty, the teacher could generate from the database a list of prerequisite skills accompanied by a list of computer programs that would help students master them. At the present time, we do not know whether such detailed databases exist. The closest we have seen are programs that store objectives to generate individualized educational programs (IEPs) for special education students and teachers.
What about the future? From the field of artificial intelligence, there is emerging a new branch of computerized education known as intelligent computer-assisted instruction (ICAI). Programs employing this strategy will look for patterns in student responses and will automatically branch to remedial units of instruction when students appear to lack the skills needed to accomplish a designated task. At the time of this writing, there are no good examples of ICAI on the market; but Mendel (Streibel and others, 1987) ADD NEWER EXAMPLES is a good example of an ICAI program in the final stages of development. ICAI is described in greater detail in Chapter 2.
Prerequisite Knowledge
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