The Key for Schools examination is part of a group of general English examinations developed by Cambridge ESOL. All five examination in this suite have similar characteristics but are designed for different levels of English language ability. Within the five levels. Ket for School is a popular exam with candidates who are learning English out of personal interest and for those studying English as part of their school studies. It is also useful preparation for higher level exams, such as Pet or Pet for Schools and other Cambridge. ESOL examinations. Ket for Schools is an excellent firsy step, helping you to build your confidence in English and measure your progress. If you can deal with everyday basic written and spoken communication (for example: read simple texts, understand signs and notices, write simple notes and emails), then this is the appropriate exam for you.