In this 9th grade physical science guided inquiry, students will work in pairs to discover the indicators of chemical reactions. Each pair of students is assigned either an exothermic or endothermic reaction. Based on their observations, students are then asked to explain the evidence that a chemical reaction occurred. Students then perform 10 more chemical reactions with unknown powders (labeled A - F) and liquids (labeled 1 - 6). They must collect data and then develop a testable question based upon all of the data collected. Finally, they answer their question by performing more experiments. For higher grade levels, the lesson plan may be modified to use appropriate equipment to demonstrate the conservation of matter.