Based on the Theory of Self-Determination we prepared an instrument to evaluate the motivation of high school students when developing activities of the Physics. We sought to evidence the scale validity, by asking an initial question: Why do I do the activities in the physics classes?." It was presented a set of 55 affirmatives, in a Likert scale with five-point. This scale was applied to a sample of 708 high school students. Were conducted the following statistical tests: factor analysis, with principal components extraction; analysis of internal consistency, descriptive statistics and the Pearson correlation. We found six representative factors: demotivation α=0.89; External Regulation - RP (Rules or Punishment) α=0.73; External Regulation - RS (Social Rewards) α=0.76; Introjected Regulation α=0.68; Identified Regulation α=0.91 and Intrinsic Motivation α=0.93, explaining 51.74% of data variability. The results indicate that we may trust the scale and we can use it in future research projects..
Motivation; self determination; physics teaching
