 Gap Fill This term refers to one of the most commonly used exercises in the English language classroom. The Gap Fill worksheet normally contains a set of written sentences which are missing certain keywords. The student's task is to fill in the missing words with the right vocabulary to complete the sentence. This type of exercise can be used to practice and reinforce the specific vocabulary or grammar points that have been taught during the lesson. Gap Fill exercises can also be used to test a student's progress as part of regular review sessions during the curriculum.