Students choosing subjects - writing introduction for some essay

I'm writting introduction for some essay. I will send it here. Please help me check my grammar and my content. Thanks a lot

1.Topic 1:
Nowadays, not enough students choose science subjects in university in many countries.

What are the reasons for this problem? What are the effects on society?

INTRODUCTION:
Today, when students participate in university courses they do not tend to select science subject. This is a popular problem with many countries in the world. It is caused by several reason and also influence on society.

One topic per thread

There are direct questions being asked in the topic. What is the reason? What is the effect? These are your discussion outline requirements. You have to present these as single sentence explanations in the restatement that you wrote. After restating the topic, you can state the reasons and effects. Make sure to choose 2 related reasons and 2 related effects so that the discussion paragraphs will be easily written on your part and clear to the reader. It is important to accomplish all of the task requirements in the opening paragraph because the TA score will depend heavily on how well you represent your English comprehension skills in that section.