Introductory science courses often have laboratory components in which students are required to write formal lab reports as homework. These reports often have problems such as incorrect data analysis, mistaken conclusions, and unclear graphs, all errors that indicate that students often fail to understand the experiments. Plagiarism is also common. To attack these problems, we required students to write lab reports in class, so the exercise was more akin to an examination. We discovered that this method yielded many benefits and considerably reduced the problems with lab reports.