This activity uses LEGO® bricks to represent atoms bonding into molecules and crystals. The lesson plan is for a 2.5 hour workshop (or four 45-minute classes). There is a "wet lab" chemistry experiment (mixing baking soda and calcium chloride with phenol red indicator), followed by a "LEGO lab" modeling phase that includes writing formulas using chemical notation. This lesson is also offered as a 2.5 hour field trip lesson at the MIT Edgerton Center.