If you're looking for an engaging STEM Lab for your unit on Rocks and Minerals, you have found it! I used this as my engagement piece into teaching about minerals, which took me about 160 minutes of instructional time. I then led into the rock cycle which took me another 220 minutes or so. The crystals the students made in this lab became a continuous topic of conversation that we'd refer back to at various points throughout the lesson. Once again, I used this as the engagement piece into my project based learning style of teaching that is already aligned to meet the NGSS Performance expectations!