This study is about the effectiveness of concept maps as a formative assessment. It aimed to investigate the effectiveness of concept maps in formative assessment for the teaching and learning of biological concepts at the secondary level. One group pretest-posttest quasi-experimental design was used for this study. The experiment was completed in six weeks. A sample of 46 students was selected from Karimabad District Hunza. Data were collected by conducting a Bioenergetics Diagnostic Test at each interval with and without intervention. It was found that concept maps are useful for the development of a clear understanding of concepts in Biology. Concept maps refrain from rote learning thus promoting critical thinking and reasoning ability and act as an effective classroom instructional and a formative assessment tool. It was concluded that the concept maps can be used as an effective formative assessment tool in Biology at the secondary level.