Ajaja, O. P. (2007). Teaching methods across disciplines. Agbor: Allwell Publishers.
 Allsops, T., & Woolnough, B. (1985). Practical work in science. Cambridge: Cambridge University Press.
 Bizar, M., & Hyde, A. A. (1989). Thinking in context: Teaching cognitive processes across the elementary school curriculum. White Plains, NY: Longman.
 Borg, W. R., & Gall, M. D. (1989). Educational research. An introduction (5th ed.). White Plains, NY: Longman.
 Das, R. S. (1985). Science teaching in school. New Delhi: Sterling Publishers.
 Dirks, C., & Cunningham, M. (2006). Enhancing diversity in science: Is teaching science Process skills the answer? Life Science Education, 5, 218-226.
 Fraenkel, R. J., & Wallen, E. N. (2000). How to design and evaluate research in education (4th ed.). San Francisco: McGraw-Hill.
 Galyam & Lecrange (2003). Teaching thinking skills in science to learners with special needs. International Journal of Special Education, 18, 84-94.
 Gavora, M. J., & Hannafin, M. J. (1995). Perspectives on the design on human-computer interactions. Issues and implications. Instructional Science, 22, 445-447.
 Hodson, D. (1990). A critical look at practical work in school science. School Science Review, 71, 33-40.
 Kenya Institute of Education (2002). Teacher’s preparation guide. The New Secondary Education Curriculum. Nairobi: Self.
 Kenya Institute of Education (2006). Secondary Chemistry Teachers Handbook. Nairobi: Self.
 Mugenda, O., & Mugenda, A. (2003). Research methods quantitative and qualitative approaches. Nairobi: Act Press.
 Mutai, K. B. (2000). How to write quality research proposals (1st ed.). New Delhi: Thellery Publications.
 National Research Council (2005). How students Learn Science in the Classroom. Washington DC: The National Academy Press.
 Ohodo, G. C. (2005). Principles and practice of chemistry education in Nigeria. Enugu: Enugu State University of Science and Technology.
 Rillero, P. (1998). Process skills and content knowledge. Science Activities, 35, 3.
 Ross, B. (2000). Modern trends in education. London: The Macmillan Press Ltd.
 Wachanga, S. W. (2002). Effects of cooperative class experiment teaching method on secondary school student’s motivation and achievement in chemistry. Ph.D. Thesis, Njoro: Egerton University Njoro.
 Wheeler, G. F. (2000). Three faces of inquiry. In J. M. Instress, & E. H. Van Zee (Eds.), Inquiring into inquiry learning and teaching in science (pp. 14-19). Washington DC: American Association for the Advancement of Science.