Which nonprojection-type teaching aid is the easiest and most frequently used?

The marker board is considered the easiest and most frequently used non-projection teaching aid because it provides a versatile platform for instructors to illustrate concepts in real-time during a lesson. Instructors can write, draw diagrams, and engage students by inviting them to contribute directly on the board. This interactive approach fosters participation and allows for immediate feedback and clarification.

Additionally, marker boards are readily accessible in most educational environments and do not rely on electricity or technology, making them convenient for impromptu lessons or in settings where electronic devices may not be available. Their simplicity and effectiveness in displaying information clearly and allowing for modifications on the fly contribute to their frequent use in various teaching scenarios.