<![CDATA[The purpose of this study is to examine the effect of formative assessment teaching strategy on students' achievement and retention in chemistry. A quasi-experimental non-randomized control group design was used in carrying out the research. Intact class number of eighty-six (86) senior secondary one (SS1) students which were randomly sampled from the population that were involved in the study. The study covered all the public secondary schools in Onitsha North Local Government Area of Anambra State. There are three research questions and three hypotheses guiding this study. The main instrument for data collection was Chemistry Achievement Test (CAT). The CAT were developed by the researchers from past West African Examination Council (WAEC) question papers to ensures content validity. The instrument (CAT) was validated by our supervisor, two chemistry lecturers and measurements and evaluation experts in Nwafor Orizu College of Education, Nsugbe. The instrument was tested and data collected was used for the test reliability estimate of (0.85) using Pearson Product Moment. Lesson plans were used as instructional tools. The data generated from the study were analyzed using mean and standard deviation and analysis of z-test. The result from the data analyzed showed that students taught using formative assessment (experimental group) achieved better than those in expository method (control group) and there was a significant difference in the students' achievement; Gender was not a significant factor in the overall achievement of students taught using formative assessment although the male students tends to show more achievement capacity than their female counterparts. Based on the findings, a conclusion was made and recommendations proffered, that the use of formative assessment teaching strategy should be adopted as an effective strategy for teaching chemistry. Hence, Educational implication and suggestion for further studies were made based on the findings]]>
