Middle school students work with many types of maps in school, however most maps they use are qualitative thematic maps that only show differences in kind as compared to quantitative thematic maps that show differences in amounts. This thesis investigates sixth-grade students' abilities to analyze three types of thematic maps: dot maps, choropleth maps, and graduated circle maps. Two hundred and two Oregon sixth-graders were tested on their abilities to interpret map symbology, make inferences from the data, categorize values into regions, and ask geographic questions concerning data distributions. The results indicate that students can understand these three quantitative thematic maps for these purposes. These results also raise the question, "Why aren't there more quantitative thematic maps presented to students in middle school curriculum?"