9A - Support systems / facility
10. Blackboard Tools
20. Audio
30. Slide Projectors
34. Film Projectors
36. Overhead Projectors
38. Video & Computer Projection
40. Photography
50. X-Y, Chart Recorders
60. Buildings
65. Museums
70. Resource Books
73. Unclassified Demonstrations
75. Philosophy
80. Films
85. Computer Programs
9B - Electronic
10. Timers
15. Position and Velocity Detectors
17. Sources of Sound
18. Sound Detectors
20. Circuits/Components/Instruments
30. Function Generators
37. Oscilloscopes
40. Advanced Instruments
50. Power Supplies
60. Light Sources
61. Light Paths Made Visible
62. Lasers
65. Microwave Apparatus
90. Computer Interface
9C - Mechanical
10. Motors
20. Pumps
25. Vacuum
30. Air Support
35. Ripple Tank
40. Other
