Low-cost experiments with water, glasses, plastic cups and bottles, rubber balloons, table-tennis balls, pill-tubes and other simple facilities of the kind never fail to attract interest of the students learning hydrostatics and thermodynamics. There is always a trap, though, of the presentational component of those amusing experiments to overbalance their cognitive and instructive impact. In such a case, efficiency of “physics toys” educational involvement could decrease dramatically. Moreover, misleading of the students towards false understanding and naive conceptions is highly possible.

Engagement of quantitative measurements and calculations into an analysis of thermodynamical physics toys and tricks may be quite helpful, as well as the speculations on their possible practical applications. Thus, adjusting a Cartesian diver to indicate pressure and temperature transforms it into an instructive measuring instrument. Just the same, an air-water filled self-made manometer may be scaled to determine atmospheric pressure with an acceptable accuracy [1] – if the students apply their knowledge of Boyle’s Law.

Variation of the parameters of traditional water/air physics toys may produce strikingly interesting devices, like presented recently in [2]. For the students and their teachers that would be an excellent involvement into creative inquiry-based studies and exciting educational research.

[1] R.M. Dieffenbach, An Algebarometer, Phys. Teach. 41, 184 (March 2003).
[2] D.R. Carpenter Jr., Another Diver/Riser, Phys. Teach. 41, 133 (March 2003).