When I first started teaching university, I noticed gaps in my student's knowledge. We would be learning about the second conditional or something like that, but my students wouldn't know what a verb was; or they'd mix up words such as fun and funny, scared and scary, bored and boring ("Nathan, you look so boring today!" they might say). Out of this need for review, I created English Survival Skills. These are small mini-lessons that I present at the beginning of class. They are designed to briefly review some prerequisite knowledge. The students know many of these points but have forgotten them and need the review. I try to make these mini-lessons as quick and entertaining as possible. I was somewhat surprised when I gave my students a survey about the class and many students said that the English Survival Skills were the most helpful part of the class (maybe I should just teach the English Survival Skills).
For examples of what I'm talking about, head to the Resources page of my site and look for English Survival Skills PPTs in the Adult ESL section of the page. I think these would work equally as well with elementary, middle school, or high school age students as well.