What are the most important factors to take into account when choosing a text for a reading lesson?

We have to keep in mind the status of the students while choosing a text for reading;

1. If they are beginners we need a simple and easy text.

2. If we are proceeding in a sequence then gradually go to more difficult ones.

3. If we want to teach some special vocabulary or grammatical lesson then we should choose according to that particular topic. 

This preferred selection will make our students more comfortable and they will take interest in learning.