Middle level students often demonstrate limited familiarity with extremes, whether in distance, time, temperature, speed, or size: and they can have poor measuring skills and an inadequate number sense. The can make scale a very difficult concept for them to grasp. To address this challenge, the concept of scale should be included at all grade levels of the middle school science curriculum. This issue of Science Scope has excellent articles that address all three of the AAAS aspects of scale—cosmic, molecular and geologic.