This paper describes two quasi-experimental studies of productive failure (Kapur, 2008) in Singapore public schools for the curricular unit on average speed. In the first study, seventh-grade mathematics students from intact classes experienced one of two conditions: a) productive failure, where students solved complex, ill-structured problems on average speed without any instructional support or scaffolds up until a teacher-led consolidation, or b) traditional lecture and practice. Despite seemingly failing in their collective and individual problem-solving efforts, students from the productive failure condition significantly outperformed their counterparts from the other two conditions on both the well-structured and higher-order application problems on the post-test. The second study, conducted in another school with significantly lower academic ability students, replicated the findings of the first study. Findings and implications of productive failure for theory, design of learning, and future research are discussed.