If you would like to do some reading on this topic, here are some suggestions:

Allwright, R.L. (1981). What do we want teaching materials for? English Language Teaching Journal, 36/1.

Alptekin, C. (1993). Target-language culture in EFL materials. ELT Journal 47/2, 136-143.

Block, D. (1991). Some thoughts on DIY materials design. English Language Teaching Journal  45/3, 211-17.

Breen, M.P., Candlin, C. & Waters, A. (1979). Communicative materials design: some basic principles. RELC Journal, 10/2.

Brindley, G. (1987). Factors affecting task difficulty. In D. Nunan (Ed). Guidelines for the Development of Curriculum Resources. Adelaide: National Curriculum Resource Centre.

Byrd, P. (1995). Materials Writers Guide. Newbury House.

Candlin, C.N. & Murphy, D. (Eds.). (1987). Language Learning Tasks. Englewood Cliffs, NJ: Prentice Hall. (Also in Lancaster Practical Papers in English Language Education; Vol. 7).

Clarke, J. & Clarke, M. (1990). Stereotyping in TESOL materials. In B. Harrison (Ed.). Culture and the Language Classroom. ELT Documents 132. London: Macmillan. Modern English Publications and the British Council. 31-44.

Coughlan , P. & Duff, P. (1994). Same task, different activities: Analysis of a second language acquisition task from an activity theory perspective. In Lantolf, J.P & Appel, G. (eds.) (1994). Vygotskian Approaches to Second Language Research.  Norwood, NJ: Ablex Press.

Crookes, G. (1986). Task classification: a cross-disciplinary review (Technical Report No. 4). Honolulu: University of Hawaii at Manoa, Social Science Research Institute, Center for Second Language Classroom Research.

Crookes, G. & Gass, S.M. (Eds.). (1993a). Tasks and Language Learning. Cleveland, UK: Multilingual Matters.

Crookes, G. & Gass, S.M. (Eds.). (1993b). Tasks in a Pedagogical Context. Cleveland, UK: Multilingual Matters.

Cunningsworth, A. (1984). Evaluating and Selecting EFL Materials. London: Heineman.

Hidalgo, A. C., Hall, D. & Jacobs, G. M. (Eds.) (1995). Getting Started: Materials Writers on Materials Writing. Singapore: SEMEO. Language Centre.

Lee, W. (1996). The role of materials in the development of autonomous learning. In R. Pemberton, S.L. Edward, W.W.F. Or, and H.D. Pierson (Eds.), Taking Control: Autonomy in Language Learning. Hong Kong: Hong Kong University Press.

Long, M.H. & Crookes, G. (1993). Units of analysis in syllabus design: the case for the task. In G. Crookes & S.M. Gass (Eds.). Tasks in a Pedagogical Context. Cleveland, UK: Multilingual Matters. 9-44.

McDonough, J. & Shaw, C. (1993). Materials and Methods. In ELT: A Teacher’s Guide. London: Blackwell.

Nunan, D. (1997). Designing and adapting materials to encourage learner autonomy. In P. Benson, & P. Voller. Autonomy and Independence in Language Learning. Harlow: Longman, 192 - 203.

O’Neill, R. (1982). Why use textbooks? English Language Teaching Journal, 36, 104-111.

Pugsley, J. (1988). Guidelines for avoiding sexism in EFL materials. Women in EFL Materials  (unpublished circular/questionnaire).

Sinclair, B. (1996). Materials design for the promotion of learner autonomy: how explicit is explicit? In R. Pemberton, S.L. Edward, W.W.F. Or, and H.D. Pierson (Eds.). Taking Control: Autonomy in Language Learning. Hong Kong: Hong Kong University Press. 149-165.

Sinclair, B. (1996). Materials design for the promotion of learner autonomy: how explicit is explicit? In R. Pemberton, S.L. Edward, W.W.F. Or, and H.D. Pierson (Eds.). Taking Control: Autonomy in Language Learning. Hong Kong: Hong Kong University Press. 149-165.

Yalden, J. & Bosquet, M. (1984). Analysis and description of communication needs and design of prototypes for the preparation of language specific pedagogic materials. Report prepared for the Department of External Affairs, Government of Canada, Centre for Applied Language Studies, Carleton University, Ottawa.