Plate tectonics is one of the most important and basic concepts required for understanding volcanic activity, seismicity, and various geological phenomena occurring within the framework of the rock cycle. Mantle convection, which refers to the thermal convection in the mantle, is the driving force for plate tectonics. Therefore, a heat convection modeling experiment was proposed for secondary school-level science students so that they can visualize and comprehend mantle convection. In this article, to improve operability and repeatability, we proposed a technique for conducting a simple experiment to model thermal convection using frozen starch syrup and localized heating; the use of starch syrup was suggested in a previous study.