sentences:  Chesswas spent 19 years in the education service of Uganda, predominantly as "Provincial Education Officer", Buganda, and finally as "Officer in Charge of the Educational Planning Unit" within the Ministry of Education.He was subsequently appointed to UNESCO on the staff of the International Institute of Educational Planners, where, as a theorist in the field of educational evaluation, he authored a number of important books and articles, collaborating with other notable theorists such as Raymond Lyons, Jacques Hallak and John Vaizey.Chesswas's works include