Internationally, second level curriculum policy for STEM education is concentrating its efforts on promoting curriculum-making pedagogies, with enquiry-based teaching and learning at the forefront of this change. Policy aspirations have not translated well into practice, evidenced by science practical lessons consistently being delivered as recipes to be followed. In recognition of this, national STEM policies are calling for quality pedagogical resources that can support teachers to engage in teaching practical work through scientific enquiry. This article describes how Design Based Research was used as a methodology to create and evaluate a resource, the Structured Enquiry Observation Schedule (SEOS), as a tool to identify student achievement of procedural (enquiry and laboratory) skills in practical biology lessons. Data collected using the SEOS, was triangulated with interview, video and audio data over three iterative research cycles. Findings indicated that the SEOS provides a lens to compare and align policy intentions with classroom enactment of practical work by identifying the basic procedural skills that should underpin any enquiry-based practical lesson, and by highlighting the importance of student attainment of those skills. If used by practising teachers, it has potential to answer calls for quality resources to support the transition to enquiry-based science pedagogy.