Why 90% is Rule of Thumb:

A teacher needs to consider a wide range of things when planning lessons or input. The teacher needs to be aware of what the students may understand and what they might not understand. Another important factor is how to deliver the content. Students are more likely to take interest when the content delivery is tailored to help them connect to it. In doing so, the students are also more likely to remember the content being taught. Teaching isn’t something that can be done on the spot, a great deal of planning must go into it to make it effective.

To help ensure comprehension, there's a few things that teachers can use and/or do. Putting up visual aids is always beneficial for students because they can reference it as needed. It also helps when the teacher uses the target language as the vehicle of instruction and provides the students with rich input. Along with the target language, gestures and motions to help reiterate the meaning of certain words helps guide the students. Essentially, teachers should focus on repetition, interaction, and reinforcement to help ensure comprehension. One big no-no is explaining something in the L1 prior to or after saying it in the target language. In doing so, students will learn to expect it and not attempt to comprehend the target language.

As teachers, we need to know that our students are capable of learning and to avoid thinking otherwise.

How to be Comprehensible

My Target Language Presentation: