| Experimental Design |
Independent Variable: Color of light
Dependent Variable: Time for leaf disk to float
Materials: light filters (red, blue, yellow, green), 7 test tubes, spinach, paper punch, baking soda, distilled water, light source, syringe, small paintbrush, foil, soap solution
1. Wrap light filters around 5 test tubes. Wrap foil to create a dark tube, and leave one tube open to unfiltered light.
2. Create a beaker of 300 mL of distilled water with 6g baking soda added. Add 12 drops of soap solution. Divide it evenly between each of the 7 test tubes.
3. Punch 35 leaf disks out of the spinach with the paper punch.
4. Put 5 disks at a time into the syringe, with some of the distilled water. Apply a vacuum pressure until disks sink. Add to one of the tubes and then keep it in the dark. Repeat to fill all 7 tubes.
5. All at the same time, place the tubes in the light and start a timer.
6. Record the time each disk takes to float.
7. Collect data on how many disks are floating, every minute, for 30 min. At the end of 30 min, throw out data for any disks that were floating at 0 or still sunk at 30. Average the time of floating for the remaining disks for each tube. |