| Proportion |
1981 |
AGENCY FOR INSTRUCTIONAL TECHNOLOGY |
15 min |
16mm |
|
sound |
| Percent |
1981 |
AGENCY FOR INSTRUCTIONAL TECHNOLOGY |
15 min |
16mm |
|
sound |
| Numerical Comparisons |
1981 |
AGENCY FOR INSTRUCTIONAL TECHNOLOGY |
14 min |
16mm |
|
sound |
| Finding A Common Unit |
1981 |
AGENCY FOR INSTRUCTIONAL TECHNOLOGY |
15 min |
16mm |
|
sound |