What to measure and how
Scientists have to decide how to record and compare attributes, often generating and using a particular scale (e.g. distance, temperature, color, moisture). Engaging students in thinking about what to measure and how to measure it helps students understand that the purpose of measurement is to support comparisons, makes measures more meaningful to them, and allows them to consider precision in ways that support data interpretation later in the investigation.
A closer look at uncertainty in the classroom
Firth grade students debating whether water increases in volume and weight as it freezes have to think about how to weigh water before and after freezing. They consider questions such as whether it would be better to weigh the water in a plastic bag and whether it is okay to weigh the water with the vial and cap before and after freezing. They consider the precision of the measuring scale and try to develop ways to measure the frozen water before it begins to melt again.
Instructional moves to support this form of uncertainty
Consider what measures will be necessary for students to record and compare findings. What might students not understand or do in a way that leads to messy data?
Consider whether you have space and time for students to collect imprecise data, recognize, and re-measure. This can be a very useful experience, but it requires support and time.
Consider showing an obviously imprecise measuring process and having students critique ad improve it before collecting data.
Present a choice – should we measure in inches or millimeters?
Where else does this form of uncertainty come up?
Explore Related Cases
Other Ways to Learn More
Consider the role of measurement in the Decomposition Investigation. How might measures support students? What might be uncertain or ambiguous about what to measure?
Read Chapter 6 of our book, Productive Uncertainty in Science Education, for more examples of uncertainty in how to measure and for advice on how to engage with this uncertainty in investigations.
