A description, including the instrument, is attached

ok thanks sir but how can i will measure learning stress of students with the help of percived stress scale.

Do  you mean linguistic stress (i.e. word stress and sentence stress)?

@Finoa: this introduces an entirely new aspect .. my assumption was that the original question was about learning stress (for which an instrument - by Cohen - exists).

@Saba Munawar: the pdf I attached includes a questionnaire which you can use. Unless, of course, you do mean linguistic stress, as Fiona Balloch suggests.

learning stress which is related to students learning.

That's what I thought. You can use the 10-item questionnaire in the pdf that I attached above. Take care that you reverse the responses as described under "Scoring". You can then compare your results with those of the norm table.

ok thanks sir.