Dear Nadya, here are some things I’d like to mention:
1st paragraph
— «the would-be teachers has to gain» use «have»
-3d sentence you shoud reconsider the word order and if we write about «benefits and challenges» wouldn’t be better to use » both challenging and advantageous»
2nd paragraph
-the would-be teacher makes while he/she teaches ??
— «his/her primary function» sounds like talking about a computer that has certain functions
-«haw to use correctly words» how to correctly use the words?
paragraph3
-«During their first lesson many students are afraid not to do something wrong and spoil the lesson, but this period helps them to overcome this feeling.» too long and not clear. What students?the ones that teach or learn? What feeling?
4th paragraph
-you could use the word «internship» itself in the first sentence not «this period» so that it is clearer.
-«taken in account» taken into account
-«an excellent opportunity to develop the would-be teacher’s skills and abilities» what skills and abilities?
You’ve done a very good job Nadya,as always!
Good luck!
damonsalvatore007 