S2.2a include appropriate safety procedures

S2.2b design scientific investigations (e.g., observing, describing, and comparing; collecting samples; seeking more information, conducting a controlled

experiment; discovering new objects or phenomena; making models)

S2.2c design a simple controlled experiment

S2.2d identify independent variables (manipulated), dependent variables

(responding), and constants in a simple controlled experiment

S2.2e choose appropriate sample size and number of trials