PURPOSE: To illustrate aspects of vector algebra.

DESCRIPTION: To provide quantitative examples, project a grid on the blackboard and read off coordinates. Demonstrate coordinate invariance by translating and rotating the grid while A+B=C is preserved by leaving the arrows fixed on the board.

SUGGESTIONS: This demonstration is for the lecture halls where magnetic vectors stick to the magnetic blackboards.

REFERENCES: (PIRA 1A40.50)

EQUIPMENT: Overhead projector with transparencies, magnetic vectors.

SETUP TIME: None.