Evaluating an Improved Technique for an Elementary School Experiment with Water Boiling

Abstract

The “three states of water” unit, studied as part of the grade 4 science curriculum in elementary school includes an experiment in which water is heated to help pupils understand that water changes into water vapor because of its high temperature. Pupils come to understand the properties of water through an experiment in which water is actually heated and its change in temperature is ascertained and recorded, allowing them to make a connection between the temperature of water and its state. Although the boiling point of water varies according to atmospheric pressure and the presence of impurities, it is widely regarded as generally being 100°C. However, with the experimental method described in the textbook, when a beaker is used as the container in which the water is poured, that temperature is shown to be 97–98°C. This is due to a problem with the specification of the bar thermometer used, but is not adequately understood by the elementary school teachers. Thus, in this study, the following two improvements were made to the beaker and the bar thermometer experimental method based on the characteristics of the bar thermometer specifications. (1) Before covering the beaker with the aluminum foil lid, a hole wider than the diameter of the bar thermometer is made in the aluminum foil. (2) A bar thermometer with a range of measurement of 0 to 200°C is used. The adjusted lesson was delivered in an elementary school science class, where it was confirmed that a measurement of close to 100°C was also obtained in the children's experiments.

In addition, when delivering the lesson, it was noted that problems with the air-conditioning environment were encountered, suggesting the air vent in the room as a possible additional factor contributing to minor variations in the students’ temperature readings.