9Trowbridge , L. W. , Bybee , R. W.& Powell, J . C. Teaching Secondary School Science. Upper Saddle River , NJ : Merrill/Prentice Hall , 2000 : Chapter 15 ,"Models for Effective Science Teaching".
10Bybee, R. W. Achieveing Scientific Literacy: From Purpose to Practices. Portsmouth, NH: Heinemann, 1997.