Teaching grammar in junior high school is very difficult, I think. It's logical teaching, so teachers can make students bored.
I think the most difficult part is "Indirect Interrogatives" Ex)We know how long you will stay in Philadelphia. Before they learn it, they have to learn affirmative and interrogative steadily.
In the part, it's important to order the words. Teachers should let them understand the interrogative order in the sentence.
I think teachers should compare "Interrogatives" with "Indirect Interrogatives". Following two sentences are example.
Where did you go?
I don't know where you went?
It's important for them to discover the differences between the sentences.