1) Have two containers ready, one with ice water a little bit above freezing, and the other with hot water just below the boiling point.
2) Fill three bottles with the lake water provided, trying to have as little duck weed as possible in them.
3) Put one of the bottles in the cold container, and one in the hot, leave the other at room temperature.
4) Using the testing equipment, measure the dissolved oxygen level of the room temperature bottle and record it.
5) Once, the hot and cold bottles have reached their designated temperatures, measure the levels of dissolved oxygen in both bottles and record.
6) To determine the percent saturation of dissolved oxygen, use the nomograph provided.
7) For the second part of the experiment, have seven bottles ready.
8) Obtain three grams of duck weed for each bottle and put it in.
9) Fill the bottles completely to the top with water.
10) Make sure there are no bugs or aquatic animals in any of the bottles.
11) Mark the cap of each bottle with: I (initial), D (dark), 100%, 65%, 25%, 10%, and 2%.
12) Using the testing equipment, measure the amount of dissolved oxygen in the initial bottle.
13) Cover the dark bottle with aluminum foil so that no light can enter.
14) Wrap black screen layers around the bottles in the following way: 100% light, no screens; 65% light, one screen; 25% light, 3 screens; 10% light, 5 screens, 2% light, 8 screens. Use elastic bands to hold the screens in place.
15) After the allotted time has passed, measure the new dissolved oxygen levels in all seven bottles and record it.
16) Calculate the respiration rate, and the gross and net productivity.