"Could" and "Can"

Question

Why has the writer used "could" in the first sentence and "can" in the second sentence?

"You could also place students in a small group of four or five. In each group, you can have at least one advanced student and at least one beginner."

Why has the writer used "can" in the first sentence and "could" in the second and third sentences:

"You can divide your students into groups by their English level. You could simply do beginner, intermediate or advanced based on your initial interaction with your students or the quality of their first few assignments. You could also test your students to get a more exact level, using a test."

Answer 1

I don't agree with VRP's answer. Both can and could can be used for permission or suggestion, and I don't believe there is any question of "permission" here.

The difference here is simply of how tentative the suggestion is. The first sentence is suggesting one out of a number of possibilities; in fact the word also makes it clear that this is an alternative to one or more suggestions already made. A paraphrase might be "here is another suggestion to consider".

The second sentence assumes that the previous suggestion has been followed, and in that case is more directive (less tentative). A paraphrase is "If you follow that suggestion, this would be a good thing to do".

Answer 2

In the first sentence, speaker is giving his permission to divide the students into groups. In the succeeding sentences, the speaker is giving his suggestions how to do. Hence "can" and "could" are used respectively.