The science assessment features hands-on experiments for a proportion of students in the sample. Why is this, and what are the experiments like?

The NAEP science framework says that "Innovative assessments in the United States and other countries use three major item types: performance exercises, open-ended paper-and-pencil exercises, and multiple-choice items probing understanding of conceptual and reasoning skills. In performance exercises, students actually manipulate selected physical objects and try to solve a scientific problem about the objects. An extra period of time (20 or 30 minutes) may be necessary for students who have been assigned to perform complex tasks." Read more about the importance of performance tasks in the science framework.

Some of the students in the sample will perform the hands-on experiments. In addition, one-half of the students in each participating school received one of three hands-on tasks and related questions. These performance tasks require students to conduct actual experiments using materials provided to them, and to record their observations and conclusions in their test booklets by responding to both multiple-choice and constructed-response questions. For example, students at grade 12 might be given a bag containing three different metals, sand, and salt and asked to separate them using a magnet, sieve, filter paper, funnel, spoon, and water and document the steps they used to do so.