Write down observations on the right side of the worksheet. Demonstrate procedure outlined on Chemical Reactions sheet, but don't spill the bromothymol blue. Discuss leveling off teaspoon to get consistent measurement. Tell students the reactions will happen quickly so they will have to concentrate and watch closely. Write down reactions on the bottom of the worksheet.
Students are amazed at the reaction.
They will want to repeat the experiment 3-4 times to validate the sequence of reactions. At the end of class period gather students back together and list reactions on the board. During this session students will design and test experiments to determine which variables caused the different reactions. Summarize the results from the last session. Note that three things went into the baggie, two dry chemicals and one fluid.