Learning grammar rules doesn't have to be dull. Some of it requires rote memorization, but the approach to teaching has changed. While worksheets will always have their place, task-based learning is starting to dominate the classroom. That is, we don't just focus on what needs to be taught, but also why it needs to be taught. So, if you're introducing adjectives, you might express its need when writing a restaurant menu.
With the "why" in the forefront of your mind, the sky's the limit when introducing new grammar tools for English learners.