Journal 4- Vernier
Last semester we were instructed to come up with an experement using a closed aquatic system, (A two liter soda bottle). My partner and I wanted to measure the amount of oxygen required to sustain the life of a gold fish, with the hope of calculating how much dissolved oxygen is produced by the elodea plants we added to the biome. We did struggle to quantify our data, and ended up having to use qualitative observations to aquire data.
One tool available from vernier, is a dissolved oxygen sensor. 
When placed in water, the sensor measures, and graphically displays, 
, the amount of dissolved oxygent in the water. It is a very simple to use tool, that would have saved us quite a bit of hassle and would have made our results more relevant. Students can certainly use this sensor, along the same lines, to measure the rate of photosynthesis in aquatic plants and/or bacteria. They could then explore the most important factors affecting photosynthesis. Students, designing their own experiments, could explore such factors as different wavelengths of light, CO2 availability, water quality, etc. These experiments could very easily cover a wide variety of biology lessons such as ecology, cell function, evolution, etc.
Something else I just think is worth mentioning is the vernier colorimeter. It provides the same data as a spectrophonmeter, concentration of a solution based on light absorbance, but is much less expensive. Vernier does have a spec. for $1200, but I don’t feel like that is necessary to introduce absorbance to high schoolers. The colorimeter only covers four wavelengths of light, which limits its use, but as I said before i think it is more than sufficent for early level biology/ chemistry lessons, and only costs $114. It is good to see that the school does not need to spend so much money to explain a concept. There is always an alternative. 
