To determine whether teaching an introductory physics course with a traditional lecture style or with Just-in-Time teaching (a student-centered, interactive-engagement style) will help students to better understand Newtonian concepts, such as Newton's Third Law, 222 students in introductory physics courses taught by traditional lecture styles and Just-in-Time teaching at North Georgia College & State University over the span of five semesters were examined using the Force Concept Inventory as a pretest and a post-test. Overall, the gains favor the Just-in-Time teaching method with a 37.6% plus or minus 2.0% gain compared to the 17.9% plus or minus 2.5% seen in traditional lecture classes. When analyzing only those gains pertaining to the Newton's Third Law questions, the results again favor the Just-in-Time teaching method with a gain of 50.8% plus or minus 4.1% while the traditional lecture classes only saw a gain of 6.6% plus or minus 5.2%. We also employed a new method of analysis which was a BIT Coding method created to quickly identify students' understanding of Newton's Third Law questions. This study shows that students in courses that are taught using the Just-in-Time teaching strategy better understand Newton's Third Law after instruction than do students in traditional lecture courses. (Contains 6 figures and 3 tables.)