This NGSS-inspired task describes a collection of experiments in which students mix unequal-mass samples of hot and cold water together and monitor the temperature until thermal equilibrium is reached. The task consists of five different activities, each taking a different angle on the experiments. Students ponder experimental design decisions, data analysis challenges, and other questions that can be asked and experimentally answered with the same or similar equipment.

This activity describes the phase changes that occur in a sample of matter as it is heated from a temperature below its melting point to a temperature above its boiling point. In addition to the two paragraphs describing the state changes, a heating curve graph is included. Questions target a student's ability to use the model presented in the body of text to interpret the graph, to connect information in the body of text to the graph, and to compare various points on the graph to one another in terms of the state of matter that is present and the process (state change or temperature increase) that is occurring.

This activity describes in quantitative terms the linear expansion that materials undergo when heated. The passage includes an equation, a table of coefficients of expansion, and a graph. Questions target a student's ability to use an equation to make predictions, to draw conclusions that are consistent with a model, to select points on a graph, to combine data from a table and a graph in order to compare the expansion of a material under various circumstances, to extrapolate outside the range of values provided by a graph, and to combine data from a table and a graph to make predictions about the amount of expansion a given length of material would undergo.