The black-board can be utilised best by a teacher for

Concept

A teaching aid earns its place by supplying something the spoken word cannot. The black-board is a non-projected visual aid, and its two defining properties are persistence and limited space: whatever is written on it stays in front of the whole class for as long as the teacher leaves it there, and only a small quantity can occupy the surface at any one time.

From those two properties a single rule follows: give the board the material whose usefulness depends on staying visible while the teacher keeps speaking, and keep everything else off it. In practice that material is the skeleton of the lesson - its key terms, definitions, headings and formulae - rather than its full text.

Applying it to this question

1. Identify what the board itself contributes: a shared, persistent visual surface that the whole class can read while listening.

2. Ask which of the described uses depends on that contribution. Writing the important and notable points does - the selected items stay in view, so a learner can re-read a term while the spoken explanation moves on, and can copy them into notes without asking for a repetition.

3. Apply the space constraint. Because the surface is small, selection is forced: the teacher must decide what is important enough to occupy it, which is precisely what 'important and notable points' describes.

4. Conclusion: the black-board is best utilised for writing the important and notable points.

Contrasting the other described uses

• Putting the matter of teaching in black and white - transferring the full lesson matter to the board makes it duplicate printed material. Board area and writing time both scale with the volume transferred, and the class spends the period copying instead of following the explanation; that is the job of a textbook, handout or e-content file.

• Making the students attentive - attention in class is produced by stimulus variation: changes of voice, position, questioning, pause and medium. Board work contributes to it, but so does every other device the teacher varies, so this names a general classroom outcome rather than the board's own function.

• Highlighting the teacher himself - this places the focus on the presenter rather than on the material displayed, so the board's visual channel carries nothing the learner needs. A teaching aid is learner-centred by definition: it exists to improve the learner's access to content.

Cross-check

The micro-teaching skill of black-board writing is taught and assessed with criteria of this kind - legibility, brevity, correct spelling, and an organised sequence of key points that mirrors the structure of the lesson - rather than by the amount of matter copied onto the surface. The standard treatment of teaching aids carries the same emphasis: a visual aid is expected to supplement the teacher's exposition, not to reproduce it.