Abstract
The study determined the effect of guided inquiry method of teaching on Senior Secondary School biology Students academic achievement and retention of concepts. One research question and two hypotheses were formulated for the study. Quasi experimental research designed involving pre-test, post test control group was employed. The population of the study was all the senior secondary school year two students (SSII) in Yola education zone. Stratified random sampling technique was used to select 119 biology students. A 50 item Biology Achievement Test (BAT) was the instrument for data collection and the same instrument was used for Biology Retention Test (BRT) but arranged differently in numbering and response option. The experimental group was taught respiration and ecology through the guided inquiry method and the control group was taught the same topics through the lecture method. The treatment lasted for four weeks. The retention test was administered two weeks after the administration of the post test. Mean and Standard deviation was used to answer the research question and Analysis of Covariance (ANCOVA) was used to test the two hypotheses. The findings shows that students taught with guided inquiry method have a significantly higher academic achievement than those taught with lecture method while those taught with lecture method retained biology concepts more than those taught with guided inquiry method. It was recommended among other things that curriculum planners should incorporate guided inquiry method in the teaching of biology in order to promote students academic achievement and lecture method should be used by biology teachers when necessary to enhance retention of concepts.