Classroom instruction should engage students in learning activities that are, to the greatest extent possible, instantiations of the real goals for learning. For example, if we want students to be able to read books, newspaper, and poems, they should, in fact, do these things and not be given shortened, simulated materials except to make them age appropriate. Similarly, in science, if we want students to be able to reason with and use scientific knowledge, then students should have the opportunity to figure out how things work by conducting investigations and developing explanations in their own words that connect their experiences with textbook theories. Assessment, then, must be conducted as part of such meaningful learning activities. Often this means that instructional and assessment tasks are merged.