"Exams in that class are easy."
I think tesuto is more commonly used, at least in junior high school. Mid-terms and finals are called 期末テスト.
You can use that as easy too. Actually, you can even connect yasui to the te form and it will mean 'easy to do (the verb you used)'
While I agree with the sentiment, it's probably useful for it to demand its use to make sure you know when it shouldn't be applied.
あの授業の試験は易しい。← I typed this but it was rejected...
あの授業の試験は易しいだ。← This is what it said at the bottom as the correction!!
Next time I see this question, I'm going to try writing it how it told me to, even though adding that だ on the end would make it ungrammatical. XD
Wouldn't クラスwork better than 授業? From my experience, 授業refers more to classes in general and the time you are in class, while クラス is more specific and refers to the course itself. Of course, they are almost interchangeable, but just because some are 外来語 doesn't make such words less Japanese
The English word "class" doesn't always mean a course either.
If the teachers write the tests for their own class, or if students are separated into different classes based on their previous year performance to which different ability level exam papers are then given, then it seems the translation could easily make sense with クラス. ^^
I see what you're saying and I think there's a possibility for that kind of usage, but for me in this specific case, since the English says "exams in that class are easy", I think the words "in that class" point to a class as in a course.
If I wanted to say "Ms. Tanaka's English class", it's 田中先生の英語の授業 (Tanaka-sensei no eigo no jugyou). Saying クラス in this case would be absolutely incorrect.
The particle for marking a topic is just は (wa), which is what is being used in this sentence. Ni would not be correct in this case.