The hundreds chart is a valuable tool for teachers in elementary mathematics classrooms. The present study investigated the effects of spatial configurations of virtual hundreds charts on children's knowledge of base-ten concepts. Kindergarten and first-grade students were assigned to three instructional conditions in which they worked with a researcher to solve arithmetic word problems. The charts used in the conditions differed by the spatial configuration of the numbers: (a) top down, with numbers increasing from top to bottom; (b) bottom up, with increases from bottom to top; and (c) explicit bottom-up, with a bottom-up chart and an explicit visual cue that prompted a comparison between the "up-is-more" structure to a cylinder filling with water. Participants were more likely to count by tens than by ones to solve problems when the numbers in the chart increased from top to bottom than when they increased from bottom to top. No effects of spatial configuration on place-value knowledge was observed. One account of the findings is that participants were more accustomed to the movements in the top-down chart because they matched the direction in which children learn to read. The role of spatial affordances of instructional materials in children's mathematics learning is discussed.