Hi, it's been almost a month. Maybe you've already found ways to deal with this yourself.
I'd still like to share some of the things I do that might work for you as well:
1. If you can decide which content topics to combine with which grammar topics, then you can look at the materials so that you can use the content (reading, listening, etc.) from a book along with the grammar exercises. That way, you can save a lot of time. Now, if your DoS gives you a syllabus to teach by where that is already decided, then perhaps you might approach him/her and ask for some tips on materials.
2. You might try to get access to a book called 700 Classroom Activities (David Seymour & Maria Popova, MacMillan). It contains very useful ideas for activities, many of which do not require a lot of preparation (but are very useful). The advantage here is that you can adapt them to the topic.
3. As a general principle, lesson planning (like everything else in teaching and learning, in my opinion) is full of trade-offs: Sometimes, you'll have an activity that is great for clarity, but perhaps the content is not very engaging. Then there are situation where you have found a very interesting text with just the right level of difficulty, but it doesn't contain a lot of the structures that you want to teach.
Keeping the context in your grammar lessons.!!
Moderator: Joe