Photosynthesis and Cellular Respiration: Learning Theories and Applications

I am going to teach my students about the cellular processes of photosynthesis and cellular respiration. In thiss essay I will explain how I am planning to teach my students. In order for meaningful learning to occur, I will need to engage my students through reception learning. Learning tasks will be thoughtfully organized and prepared so that they are relevant and allow students to connect to prior learning. I always use some type of “pre-test/activity” to gain insight and data into what the students already know.

Teaching Plan: Exploring Photosynthesis and Cellular Respiration

I will begin by considering cognitive structures and build beginning with more general, stable ideas and moving toward more specific, unstable ideas. For example, typically all pre-concept data shows that my students are familiar with plants and animals, they are familiar with the exchange of materials and flow of nutrients between plants and animals. In addition, they have already learned this year (because I taught them) about macromolecules like glucose and the organelles within the cell like the mitochondria and chloroplasts. This allows me to anchor these new ideas into what they already know.

We begin lecture recalling which organelles plants have (both chloroplasts and mitochondria) and which organelle animals have (mitochondria only). We also recall that chloroplasts assist in helping the plant to make its own food and that mitochondria help the animals to create energy from their food. We differentiate between autotrophs (plants/algae/bacteria) that make their own food for energy and heterotrophs (animals, fungi) that need to consume food for energy. We recall the important molecules of H20, CO2, glucose, ATP and O2. Lastly, discuss the flow of these materials between plants and animals and the environment. We can create a flow chart or tables to organize this information by which terms apply to plants, animals, or both. This allows me to then move forward with subsumption and add new ideas to this pre-existing knowledge.

This example would be considered derivative subsumption because we are now adding examples to our old ideas. Now that my students are ready and have recalled the basics from previous learning, we can begin learning the new ideas and concepts. We discuss new ideas like catabolic and anabolic as ways to describe these processes. We discuss new pathways involved in each process. These ideas are then added into our organizer/flow chart and connect to our original ideas.

I prefer to focus on photosynthesis first in isolation learning about all the steps in the process of autotrophs creating glucose from the reactants. I can then use combinatorial learning to add the concept of cellular respiration because the concepts are so similar. I explain that it is simply the opposite or photosynthesis in reverse. They recognize that they are connected and if you understand one, you can easily understand the other. I like to use charts here to differentiate and compare one to the other. I like to do both lecture and hands on labs illustrating these connections.

Lastly, superordinate learning comes into play when I want to discuss ATP. The students have already learned about this molecule in a previous chapter and again when we discuss photosynthesis and cellular respiration. However, they are able to come to the conclusion of its importance in ALL living things only after learning about cellular respiration and photosynthesis. It is subsequently subsumed and is a more general idea, however, it is hard to understand its importance until we truly understand these other processes first.

Using Bruner’s Models for Learing About Photosynthesis and Cellular Respiration

Again I am going to use the example of teaching my student’s about the process of photosynthesis. Using Bruner’s three modes of representation, I feel I can best reach all of the students in my classroom in the way that they best structure their understanding of the concept. Students do have some prior knowledge but are not yet capable of iconically or symbolically representing the material so I believe beginning with the enactive stage works best here.

Our first activity will consist of an enactive representation using marshmallows and toothpicks to manipulate the products and reactants of photosynthesis. I will give them enough to build the reactants and then they must take them apart and restructure them as products. This will allow students to see the reactant molecules be transformed into products. All atoms (marshmallows) are used on both sides they are just in a different form. This lays the ground work for what happens within the chloroplast of the plant cell.

Secondly, we will employ iconic representation through pictures and diagrams to walk through the steps involved in this process. Students will draw their own pictures to show how reactants become products through photosynthesis. I call this visual notetaking.

Finally, symbolic representation will be used showing the formula that represents photosynthesis using symbols instead of words. In our laboratory investigations, products and reactants will be coded into the scientific formula that scientists and that is used in their textbook. Students are now expected to recognize and represent molecules in this form.

Conclusion

These activities also lend themselves to another of Bruner’s theories called discovery learning. They allow the students to work through the problem on their own and come to their own conclusions about photosynthesis and reflect upon their solutions. I am the guide and will step in as needed to help the students in their discovery. They use inductive reasoning to move from specific ideas to create more general understandings. I have recognized the intrinsic value of discovery learning. Students who are able to problem solve and recognize patterns have a better connection to the material and are more motivated to learn as Bruner suggests in this theory.

Bruner also believed that culture plays a large part in one’s intelligence and cognitive development. I have noticed several things over the years how a student’s culture can impact their performance on this very topic. Typically, students who have grown up living on their family’s land and helping to raise the animals and plants gives them much more background information when it comes to learning about photosynthesis. I wouldn’t have guess it, but they are able to apply those enactive lessons to be able to more quickly jump into the iconic level. Secondly, I have seen my Hispanic students (English language learners) typically grab onto the symbolic representation more quickly simply because those letters and numbers are standard across language and across cultural barriers. I adjust the types of activities and the order in which we do them based on which types of children are in the class.