Engineers start by defining the problem precisely: what the design must do (criteria) and what limits it (constraints). This week the crew designs a scale model of the solar system for the family. The criteria are that the planets are in the right order, the distances follow one scale and every marker is labeled. The constraints are that it fits the hallway or yard, uses household materials and is finished in one week. The crew builds it from NASA distance data, tests it with a tape measure, improves it, and writes the Earth and Space report that gathers every week's Sky Log.