In March 2019 the Ministry of Education (MOE) commissioned NZCER to conduct an exploratory study of curriculum levelling in the Science and Mathematics and Statistics learning areas of "The New Zealand Curriculum" (NZC). The study was prompted in part by a desire to probe possible reasons for patterns of achievement reported by the National Monitoring Study of student Achievement (NMSSA). Results from NMMSA have shown "persistently low levels of achievement at year 8 relative to year 4" (MOE Statement of Work). These results raise questions about the comparative difficulty of curriculum expectations at these two levels. The programme was comprised of four interrelated components that involved: (1) identifying what is known about the difficulty of the curriculum, using existing evidence from NMSSA; (2) considering insights from recent comparisons of NZC with curricula from other jurisdictions; (3) consulting curriculum expert groups for their advice about the appropriateness of curriculum expectations; and (4) eliciting teachers' experiences and views about curriculum levelling at a series of focus groups.