When the thermal expansion of water is discussed in school or university lessons, functional relationships are often inferred without considering measurement uncertainties. Moreover, in some learning materials, the goal of experimentation and the experimental setup do not match. This creates the wrong picture of scientific practice. In this article we compare five experimental setups with different complexity to investigate the relationship between heat and volume change of water. We take different goals of experimentation into account, as well as measurement uncertainties. We compare the different experimental setups, show advantages and limitations, and give advises for their implementation in the classroom. By doing so, we demonstrate that thermal expansion can be very well adopted for applying scientific practice in school. It is shown that the more complex the experimental setup, the more precise the quantitative significance of the functional relationship.

在学校或大学课程中讨论水的热膨胀时，通常会在不考虑测量不确定性的情况下推断函数关系。而且，在一些学习材料中，实验目标和实验设置不匹配。这造成了科学实践的错误图景。在本文中，我们比较了五种不同复杂度的实验装置，以研究水的热量和体积变化之间的关系。我们考虑了不同的实验目标以及测量的不确定性。我们比较了不同的实验设置，展示了优点和局限性，并为它们在课堂上的实施提供了建议。通过这样做，我们证明了热膨胀可以很好地用于在学校应用科学实践。