Question

If the teacher is standing 15 feet away from the blackboard, the size of the letters should be:

• A. 5 - 8 inches
• B. 10 - 12 inches
• C. 12 - 15 inches
• D. more than 15 inches

Hint:

Exam Tip:
A useful memory aid:
Distance (in feet) \(\times\) 0.33 to Distance (in feet) \(\times\) 0.5
For 15 feet: \(15 \times 0.33 = 5\) inches to \(15 \times 0.5 = 7.5\) inches.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
This question tests the principles of visual aids and the design of effective blackboard writing, similar to question 91. The required letter size depends on the viewing distance.

Step 2: Key Formula or Approach:
A general rule of thumb for letter height is based on the viewing distance.
For every 10 feet of distance, the letter height should be at least 0.5 to 1 inch.
However, for a blackboard, the teacher's distance from the board (15 feet) is different from the students' distance.
When a teacher is writing on the blackboard, the students in the last row need to see it clearly.
If the teacher is 15 feet away from the board, the students are likely further away.
The question, however, asks about the size of letters from the teacher's perspective or for optimal visibility in a classroom.
A more practical rule: Letter height = (Distance in feet) 2 to (Distance in feet) 1.5.
For 15 feet:
Minimum height = \(15/3 = 5\) inches.
Maximum height = \(15/2 = 7.5\) inches.
This is approximately 5 to 8 inches.
The key is that the letters should be large enough to be seen by the entire class.

Step 3: Evaluating the Options:

• (A) 5 - 8 inches: Matches the calculation.
• (B) 10 - 12 inches: Too large; would be for billboards.
• (C) 12 - 15 inches: Much too large.
• (D) more than 15 inches: Impractical.

Step 4: Final Answer:
The size of the letters should be 5 to 8 inches. Therefore, option (A) is correct.