In this Activity, students extract a fluorescent substance from shavings of narra wood. The pH-dependent fluorescence can be turned on and off using household acid and base solutions. A yellow filter blocks the exciting light but not the fluorescent emission. This Activity gets students thinking about the interaction of light and molecules.
In this Activity, students dye fabric squares with two plant dyes: aqueous extracts of tea leaves and of marigold flowers. They investigate how the addition of iron to a dye bath affects the resulting color and fastness of the dyed fabrics and observe that the type of fabric affects the results. This Activity can accompany a discussion of the impressive array of chemicals produced by plants.