S2.1 Use conventional techniques and those of their own design to make further observations and refine their explanations, guided by a need for more information.

S2.2 Develop, present, and defend formal research proposals for testing their own

explanations of common phenomena, including ways of obtaining needed observations and ways of conducting simple controlled experiments.

S2.3 Carry out their research proposals, recording observations and measurements

(e.g., lab notes, audiotape, computer disk, videotape) to help assess the explanation.