The purpose of assessment activities used at the beginning of a teaching sequence is to ascertain students’ existing understandings. Teachers make observations of what is happening in their classrooms all the time. Assessment is important not only because it informs students about what they know and can do in science, but also because it helps teachers to plan future lessons. Collecting evidence around student achievement in science requires quality items that are fair and equitable and give all students the chance to achieve in science. Tests and examinations can be effective and highly appropriate mechanisms for assessing what students know, understand and can do in particular areas of science if used appropriately. The same occurs with international tests, such as Programme for International Student Assessment and Trends in International Mathematics and Science Study.