This paper reports on a study carried out at a University of Technology, South Africa, aimed at identifying the existence of the mathematical knowledge gap and evaluating the intervention designed to bridge the knowledge gap amongst students studying first year mathematics at the Chemical Engineering Extended Curriculum Program (ECP). In this study, a pre-test was used as a diagnostic test to test incoming Chemical Engineering students, with the aim of identifying the mathematical knowledge gap, and to provide students with support in their starting level of mathematical knowledge and skills. After the diagnostic test, an intervention called the autumn school was organized to provide support to bridge the mathematical knowledge gap identified. A closed Facebook group served as a platform for providing student support after school hours. After the autumn school, a post-test was administered to measure whether there was an improvement in the knowledge gap. Both quantitative and qualitative methods of collecting data were used in this study. A pre-test was used to identify the mathematical knowledge gap, while a post-test was employed to measure whether there was a decrease in the knowledge gap after the intervention. Focus group interviews were carried out with the students to elicit their opinions on whether the intervention was of any help for them. Students' participation on Facebook in terms of student post, post comments and likes and an evaluation of students' academic performance in comparison to their Facebook individual participation was also conducted. Quantitative data was analysed using descriptive statistics, while qualitative data was analysed using inductive strategy. Results showed that all the students in this study had the mathematical knowledge gap as no student in the class scored 50% on the overall pre-test. Findings further revealed that the intervention played a major role in alleviating the mathematical knowledge gap from some of the students (with 1/3 of the students scoring 50% and above in the post-test) and no positive correlation between students' academic performance on the post-test and students' participation in the Facebook group was noted. We hope that insights generated in this study will be of help to other institutions looking into designing interventions for bridging the knowledge gap. Reasons for lack of improvement in the knowledge gap of 2/3 of the students in this class will be highlighted.