Students in acoustic phonetics and speech science classes often do not have much technical background; an intuitive means to teach acoustic phenomena to them would, thus, be useful. Regarding speech production, physical demonstrations using vocal-tract models have been shown to be an intuitive way to teach acoustic phenomena. In particular, a series of models for different purposes has been developed by Arai over the last 20+ years, including lung models, sound sources, and vocal-tract models, e.g., see Arai [J. Acoust. Soc. Am. 131(3), 2444-2454 (2012)]. Different combinations of these models are helpful for teaching a variety of related topics in the classroom. However, there are still barriers to understanding certain concepts. This study examined ways of minimizing technical explanations and mathematical formulations and maximizing intuitive understanding of seven topics. Its findings were incorporated into an education program that was used in an actual lecture conducted online. A comparison of scores of questionnaires filled out by the audience before and after the lecture showed the program's effectiveness, especially in relating how a set of harmonic waves excites a multiple-resonance system and how the vowel /a/ is produced.