| 摘要 |
<p>The device allows the student response to a question to be ascertained at a glance by the teacher, by employing a cursor disc which is slid along the rule by the student so as to be brought into alignment with one of a selected number of answers to the question, provided along the length of the rule. The rear of the rule is provided with distinct visual markings, on a strip which is threaded through two aligned slots in the disc, so that the position of the latter determines the visual marking on view, each marking corresponding to one of the answers provided along the front of the rule.</p> |
