Conclusion The findings in the investigation reported in this paper suggest that items in
the primary school national examination in Singapore that were classified as
challenging were challenging for several reasons. Some were challenging because
pupils need to go beyond computational proficiency to succeed. Pupils who succeeded
had ‘big math ideas’ such number sense, visualization, patterning and modeling.
Others were challenging because pupils required suitable heuristics to simplify
difficult ideas. It was found that diagram-type heuristics were of particular help for
many pupils. And yet others were challenging because pupils needed good habits of
mind to make the leap to a correct solution.