Inquiry and NSES Analysis/Lab

September 13th, 2010 | Uncategorized |

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This lab demonstrates rates of transpiration in plants. Transpiration is water vapor being evaporated from the plant, similar to sweating in animals, and occurs mainly off of the leaves. This lab deals with two questions about transpiration: 1) What role does the number or size of the leaves play in the movement of water through the plant, and 2) which force plays a more important role in the movement of water through a plant, the absorption of water through the root, or the evaporation of water by the leaves?

This lab is definitely a level 2 on the Herron Scale of Inquiry. The teacher presents the two questions, but the students design the experiment and carry out their own procedure. With the proper background knowledge, this is not an impossible task for students either, and I would bet that the majority of AP students and probably many non-AP students would still be able to figure out how to properly solve these questions. Furthermore, the students would not need lab experience to do this, and the only “costly” materials would be test tubes, so this lab could be done early on in the school year as a good way to gain lab experience before using more complex and expensive lab equipment.

With respect to the NSES Content Standards, this experiment reflects standards A and C, Science as Inquiry and Life Science, respectively. For standard A, the students “identify questions and concepts that guide scientific investigations”, “design and conduct scientific investigations”, and “communicate and defend a scientific argument.” For standard C, this deals with behavior of organisms. Specifically, it would deal with organisms (the plant) responding to internal (amount of water) and external (temperature, humidity, light intensity, and wind speed) stimuli.

This lab also reflects the “Science Teaching Standards #2: The actions taken to guide and facilitate student learning.”  Although the students have some background on transpiration and other plant processes, they should not know the answer to these questions before the lab. Therefore, the lab (and teacher who will guide them through the lab) will guide and help the students learn the material on their own, without explicitly telling them the answers.

Overall, this is a great lab and experiment. It is safe, easy, cheap, and conducive to student learning. It would also be a great way to get students to work together, especially when designing their procedure.

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