Investigated the learning by eighth-grade students of the concept of crustal evolution, asking questions that deal with how time-efficient procedures can be devised that measure concept learning effectively and whether these procedures yield valid information on the learning of a science concept. (CS)

Several studies of the validity of the intensive time-series design have revealed a post-intervention increase in the level of achievement data (the "momentum effect"). Reports on the development and use of a technique to study the effect as it is observed in several data sets on the learning of plate tectonics. (Author/JN)

This study examined whether the intensive time-series design would yield data discriminating between concrete and formal operational students and whether achievement curves exhibited in previous studies would be found with students in this study. Daily measurement of variables is characteristic of the data collection procedure in the time-series…