You need a fun, engaging, minimal set up and low cost lab? This is it! I really enjoy doing these labs and as I ask questions, watching when my students get that “ooohhh I get it now!”  This lab is all set up for you with the question "Which color M&M dissolves quicker". It has the steps broken down so it allows students to practice the steps. It provides observation questions for students to ponder. Then has a collaboration piece which does save time if your time is limited with not having to do repeated trials, although, I do emphasize the importance of having to repeat the experiment and get the same results.  I know you and your students will enjoy this!