This Instructional Activity is a part of the Lesson 13, Unit 4, Grade 7. This activity has students measuring things around the classroom to connect to the previous activity about measurement error. Students will work with their partner to measure 3 different things found in the classroom that the teacher has measured ahead of time (to obtain an "actual" measurement). They will use two different rulers (one with mm markings and one without). After both students in a group have measured their three objects, provide them with the actual measurements of those items. They will calculate the measurement and percent errors after given the actual measurements.