The teaching content of this resource is endorsed by OCR for use with specification GCSE (9-1) Gateway Science Combined Science A J250. However, as specifications are updated over time, there may be contradictions between the resource and the specification, therefore please use the information on the specification for J250 and the Sample Assessment Materials at all times when ensuring students are fully prepared for their assessments. Endorsement indicates that a resource is suitable to support delivery of an OCR specification, but it does not mean that the endorsed resource is the only suitable resource to support delivery, or that it is required or necessary to achieve the qualification. OCR recommends that teachers consider using a range of teaching and learning resources based on their own professional judgement for their students’ needs. OCR has not paid for the production of this resource, nor does OCR receive any royalties from its sale. For more information about the endorsement process, please visit the OCR website.