Phonological third tone sandhi studies in Mandarin Chinese will lead more often to a lab-centered research, whereas the incorporation of phonetic tone sandhi studies into phonological analyses will shed a light on a classroom-centered study. This incorporation suggests a revised approach to the third tone sandhi from an articulatory perspective. As a result, the study of pitch values and pitch contours of a third tone are taken over by the study of sound positions and jaw/chin movements. The well-known five-level tonal diagram is challenged and replaced by a seven-level tonal diagram with an application of only two forms of pronouncing a third tone ---pseudo third tone and pseudo second tone. All these aim to investigate a classroom-centered study of a third tone as an understudied area to provide practical guidance for Mandarin instructors and learners of Mandarin as second language.