What is a fun way to teach Grammar?

You should make your whole class participate in your lessons. You could create a point system and that if more kids participate they'll get points and reward them with parties. pizza party, snack party, etc.

By giving some examples and keeping the oral explanation to the very minimum. Then some exercise questions on the board, allowing your students to try first in their work books and then ask who would like to try for to supply the answer. I have always fiound it easier to teach grammar through construction using exercises such as missing word passages, multiple choice questions and rewrites ( transposition). An examples of the latter, in case you are not familiar with them are, 1.a) Tom is much taller than Peter. b) Rewrite using the correct form of the word 'short' 2.a) John did not pass the exam. Mary did not pass either. b) Rewrite as one sentence without using 'and'. Above all keep the lessons 'student orientated' with the teacher acting as a sort of animator. Occasionally ask a serious student to come to the board to write or explain the answer. it is a slower method, but, I think, more effective.