Accordingly, the language used in the narration is kept very simple. The segments are usually narrated by an off-camera voice. Sentences are short. "Big words" are not used, and difficult concepts are broken down and described while they are being shown on camera. This is designed to free children from the more abstract concepts and devices of language, thus giving their minds space to comprehend the concepts explained rather than having to struggle comprehending the language of the explanation. Nonetheless, the educational film shorts are such effective presentations of their subject matter, a number of them are used as teaching tools at universities and colleges.