This research study aimed at investigating the effectiveness of using the ASSURE Constructivist Model supported with multimedia to improve English speaking skills for science and math teachers at the preparatory stage. Ten teachers at Al-Shaheed Ahmed Galal and th January Governmental Schools with some lack of speaking subskills -as indicated by the pretest- were purposively selected to participate in the study. The researcher used the one-group pre-post test quasi-experimental research design in the light of which a speaking pre-post test was designed along with an English speaking sub-skills checklist to assess the participating teachers' improvement in the specific speaking skills before and after using ASSURE Model supported with multimedia. The results demonstrated that there was a statistically significant difference at level between the mean scores of the research group in the pre-post administration of the speaking test in favour of the post-administration. It was found that using ASSURE Model supported with multimedia achieved high effectiveness in improving the speaking sub-skills of science and math teachers.