Owolabi, Henry OlumuyiwaSheu, Adaramaja LukmanOgunjimi, Mayowa OlurotimiOlutola, Thomas Adekunle2019-06-102019-06-102012-031116-0381http://hdl.handle.net/123456789/2094Formative assessment is used by teachers and students during instruction to improve students’ achievement of intended instructional outcomes and motivation. However, the impact of formative assessment by the secondary school teachers is regrettable. Hence, this study aimed at investigating the teachers’ perception of impact and challenges of using formative assessment in improving students’ achievement motivation. Three research questions were generated and descriptive survey research design was used in the study to collect data from a sample of one hundred and fifty Senior Secondary School teachers in Ilorin, Kwara State. The instrument for data collection was a validated questionnaire on teachers’ perception of formative assessment (QTPFA). The result of the data analysis showed that the most perceived impact of formative assessment allows students to receive feedback about the quality of their work and what they can do to make it better. Also, the study revealed that poor time allocation and teachers’ resistance to further the testing of students is the most perceived challenge of using formative assessment in the classroom. It was recommended that teachers should be motivated to design how best to adapt formative assessment to their needs and the needs of their students and that assessment guidelines and monitoring committee should be set up by the government in order to ensure high quality formative assessment practicesenFormative AssessmentSummative AssessmentMotivational StrategiesSelf-learningArticle