For Lesson 75, students were challenged to identify a procedure to count large numbers of objects using only a small sample of those objects.  The lesson began with the Lesson 75 PowerPoint ChemCatalyst activity.  We worked through part A and then students were challenged to complete part B as homework for 5 points of extra credit.  Notes from the activity are pictured below:

Students then received the Lesson 75 Worksheet and worked together in small groups to come up with and enact a common procedure to count unknown numbers of toothpicks, pinto beans, Eppendorf tubes, pipette tips, lentils, and keyboard keys.  An abbreviated procedure  is in the picture above and class results (calculated and actual) are pictured below.