Science education is not just about learning facts in a classroom--it's about doing activities where students put their understanding of science principles into action. That's why two unique types of activity-based tasks were administered as part of the 2009 National Assessment of Educational Progress (NAEP) science assessment. In addition to the paper-and-pencil questions, fourth-, eighth-, and twelfth-graders also completed hands-on and interactive computer tasks. These tasks help stakeholders understand not only what students know, but how well they are able to reason through complex problems and apply science to real-life situations. While performing the interactive computer and hands-on tasks, students manipulate objects and perform actual experiments, offering us richer data on how students respond to scientific challenges. This paper reports the following findings on student performance across the tasks: (1) Students were successful on parts of investigations that involved limited sets of data and making straightforward observations of that data; (2) Students were challenged by parts of investigations that contained more variables to manipulate or involved strategic decision making to collect appropriate data; and (3) The percentage of students who could select correct conclusions from an investigation was higher than for those students who could select correct conclusions and also explain their results. Technical notes are included. (Contains 9 tables.)