I will report on an ongoing longitudinal study of the impact of school input on spatial growth.  Individual differences in spatial skill levels often have been attributed to biological factors -- for example, the ability to do rotational transformations.  In earlier work we found that input also has major effects on spatial growth.  We tested a population of kindergarten and first grade children at four time points that were 6 months apart.  If growth were due to biological factors, performance should increase smoothly over time. But we found that growth was much more rapid over the school periods than over the summer.  Since we tested the same population at different time points, it is clear that input is critical to growth.  In our present work we are using this design to explore spatial growth in second and third grade children in widely different schools.  We have developed spatial scales in addition to the rotational transformation task we used earlier.  In this study we are investigating differences in growth in different classes.  We also have developed measures of spatially relevant input in the classroom. We are examining how variation in growth is related to variation in input by looking at the amount of growth over the school years in different classes.  Our aim is to determine the malleability of spatial skills, and to identify what curricula are associated with the greatest growth.