The Instructional Practices Log in Science (IPL-S) is a daily teacher log developed for K-5 teachers to self-report their science instruction. The items on the IPL-S are grouped into scales measuring five dimensions of science instruction: "Low-level Sense-making," "High-level Sense-making," "Communication," "Integrated Practices," and "Basic Practices." As part of the current validation study, 206 elementary teachers completed 4137 daily log entries. The purpose of this paper is to provide evidence of validity for the IPL-S's scales, including (a) support for the theoretical framework; (b) cognitive interviews with logging teachers; (c) item descriptive statistics; (d) comparisons of 28 pairs of teacher and rater logs; and (e) an examination of the internal structure of the IPL-S. We present evidence to describe the extent to which the items and the scales are completed accurately by teachers and differentiate various types of science instructional strategies employed by teachers. Finally, we point to several practical implications of our work and potential uses for the IPL-S. Overall, results provide neutral to positive support for the validity of the groupings of items or scales.