Various gap-filling exercises

Gap-filling exercises are commonly used to check understanding of new concepts in grammar books and such. They also tend to appear in tests for vocabulary. The beauty of the gap-filling exercise is that they are flexible and you can quite easily vary their level.

Beginner's level
Very suitable for beginners or when testing new concepts is the initial gap-fill level. You take a limited set of sentences (no more than ten) and provide the words that need to be used above or below the exercise. In this way, it becomes a bit more like a multiple choice question because students will fill out the ones they're sure about, dividing the remaining words among the ones they don't know. You can make this a bit harder by adding one or two words that don't need to be used. Be sure to mention this in the instructions.

The one thing to look out for is that you're really only testing one aspect: either content or form. In a vocabulary exam, students should not have to consider whether the word is in the correct form as that is an unfair addition to the test. Conversely, if your goal is to test language structures, you should not use words the students might not know as this adds an extra dimension to the test that shouldn't be there. You could follow the test task Cambridge ESOL gives in that they provide the basic form of the word next to the gap and the test-takers must provide the altered form. For example, if the word in the gap should be unbelievable, they will offer as input belief.

Intermediate level
This intermediate level is only suitable for vocabulary tests. You do the same as above, but this time you don't provide the words, but only the initial letter. In this way students get some help in deciding which word it may be without giving away as much as at the beginner's level. Specify clearly how many words should fit in the gap. It would obviously be easier to do when students have been given a specific set of words to study, but you can also test their creativity and vocabulary depth if it is unrelated to words discussed in class.

Advanced level
The hardest thing to do is obviously to fill the gap without any clues whatsoever. This type of exam is called a cloze test and is regularly used to get a quick overview of someone's level in that language. In such cases the gaps are in a text and carefully chosen to reflect various levels of difficulty. Students need to not only decide what word contextually fits in the gap, but also which form it must take, so it is a combined test of vocabulary and grammar. A cloze test can be offered on paper, but also as a listening test.

Conclusion
No matter what level you make the test, it would ideal if you can do a pre-test with a couple of students to see whether you're on the right track. In all, the higher level exercise you give, the more freedom they should be allowed in their answers. Just because something wasn't in the textbook shouldn't mean a valid answer is deemed unacceptable.