5-25  Marker Board  Types of Instructional Aids  Instructional aids should appeal to the learner and be based on sound principles of instructional design. When practical, they should  encourage learner participation. They also should be meaningful to the learner, lead to the desired behavioral objectives, and provide  appropriate reinforcement. Aids that involve mastering a physical skill should guide learners toward mastery of the skill or task  specified in the lesson objective.  Instructional aids have no value in the learning process if they cannot be heard or seen. Recordings of sounds and speeches should be  tested for correct volume and quality in the actual environment in which they will be used. Visual aids should be visible to the entire  class. All lettering and illustrations need to be large enough to be seen easily by the learners farthest from the aids. Colors should  provide clear contrast.  While many instructional aids come with purchased material, the effectiveness of instructor-produced aids and the ease of their  preparation can be increased by initially planning them in rough draft form. The rough draft should be carefully checked for technical  accuracy, proper terminology, grammar, spelling, basic balance, clarity, and simplicity. Instructional aids should also be reviewed to  determine whether their use is feasible in the training environment and whether they are appropriate for the learners. See the figure for  a summary of the desired qualities of instructional aids.  [Figure 5-17]  Some of the most common and economical aids are marker boards and supplemental print materials, including charts, diagrams, and  graphs. Other aids include projected material, video, computer-based programs, and models, mock-ups, or cut-aways.  The marker board is a classroom tool for instructors. Its versatility and effectiveness provide several advantages for most types of  instruction. First, the material presented can be erased, allowing the surface to be used again and again; and second, the boards serve  as an excellent medium for joint learner-instructor activity in the classroom.  Figure 5-17.  Guidelines for effective instructional aids. 