Analyzing a Biology Textbook for Instructional Purposes

Michigan High School Content Substandard Used: B3.2 Ecosystems

Catherine S. Quist

October 8, 2006


Textbook Used

Title: Annotated Teacher's Edition BSCS: A Molecular Approach Blue Version 8th Edition
Publisher: Everyday Learning Corporation
Date of Publication: 2001
Authors: Jon Greenberg
Specific Subject: Biology
Grades: 10 & 12
Age: 15-18
Ability Level: Honors

Unpacked Learning Goal

Biology - Unpacking Ecological Energy Flow

Analyze Selected Features of the Materials

The following table looks at the performance expectations for the Michigan High School Content Substandard: B3.2 Ecosystems. For each performance expectation, the textbook has been evaluated based on three criteria from Project 2061.

Category III: Engaging Students with Relevant Phenomena
  • Criterion III.A: Providing a Variety of Phenomenon
  • Criterion III.B: Providing Vivid Experiences

Category IV: Developing and Using Scientific Ideas
  • Criterion IV.B: Representing Ideas Effectively

For more information on these criteria, see: http://www.project2061.org/publications/textbook/hsbio/report/crit-used.htm

Table:

Modification I'd Make in Light of My Evaluation


A major weakness of the BSCS Biology: A Molecular Approach textbook is the lack of vivid experiences for the students. The textbook does provide lab activities for the students, but these tend to be larger scale chemistry based experiments. At the end of each chapter, the textbook also provides three or four extension exercises. These tend to be fairly rote and don't really illustrate key concepts. I've noticed that other textbooks, such as Biology: The Dynamics of Life published by McGraw Hill, have a lot of small activities embedded throughout the textbook. These activities are designed to provide vivid experiences, and as such they help the students make conceptual connections with the material being taught. These sorts of activities are especially important in teaching abstract concepts, such as energy flow in ecosystems, which are better learned through manipulation of the concepts. As a teacher using this textbook, I'd need to design multiple in-class activities designed to provide vivid experiences, since I wouldn't be able to rely on the textbook to provide them.

Teaching Energy Storage in Ecosystems: This textbook does not explicitly describe energy storage in an ecosystem. While Chapter 2: Energy, Life, and the Biosphere does cover energy in ecosystems and energy storage in molecules it does not explicitly connect the two. Most of the figures in the book connect molecular synthesis and decomposition to energy flow, however there are no figures connecting the molecular scale with the organismic scale. If I were teaching this performance standard, I would first explain molecular energy flow. I would show the connection between energy storage and the major macromolecules. I would do this by providing a flow diagram showing how sugars, fats, starches and proteins are interconverted via their building blocks, releasing and storing energy in the process. I would also use the phenomenon of glucose and glycogen interconversion to illustrate how the breakdown and formation of macromolecules releases and stores energy, showing the students Figures 2.14 and 2.15. Next, I would connect the flow of energy at the molecular level with the flow of energy at the organismic level by providing the students with a picture showing a plant in a food web with a little diagram showing photosynthesis inside of it and a deer in a food web with a little diagram showing cellular respiration inside of it. Finally, I would use the example from Figure 2.10 of a plant developing from a seed to a seedling to a mature tree as an illustration of the idea that the energy that is not released as heat is stored in increasingly organized biological structures.

Teaching Energy Transfer in Ecosystems: The textbook provides the example of the wolf eating the deer to illustrate energy transfer in ecosystems. I would want to provide the students with the diagram (Fig. 2.8) from the textbook that explicitly shows the relationship between the wolf eating the deer, digesting the deer meat to release macromoleculese, decomposing the macromolecules to release energy, synthesizing the resulting building blocks into new macromolecules. I would then show the students a picture of a food web showing the loss of energy at each connection in the food web. This figure is not provided by the textbook. Next, I would show the students Figure 2.11, which shows the transfer of energy between producers, consumers and decomposers, indicating that energy is lost as heat during each transfer. Finally, I would use the energy pyramid shown in Figure 24.4 to illustrate the connection between the loss of energy between each trophic level and the biomass of each trophic level. Since there are no vivid experiences of this performance expectation in the textbook, I would add a food chain based outdoor activity that illustrates the relationship beween the loss of energy in a food chain and the biomass of the trophic levels.

Teaching Energy Flow in Ecosystems: The textbook provides a picture of a food web (Figure 2.6). I'd first show this to my students to give them an idea of what a food chain looks like. I'd explain that each arrow in the food chain represents the transfer of energy and matter, and that it points in the direction of energy and matter flow. Next, I'd point out that decomposers are at every level of the food web. I'd also point out that the organisms can be grouped based on whether their producers or consumers and that this results in a simplified diagram of energy flow in the ecosystem, which is shown in Figure 2.5. I'd remind the students that energy is lossed during each transfer. Next, I'd work with the students to have the vivid experience of constructing a food web on the blackboard. I'd have the students draw three parallel food chains from a particular ecosystem and then guide them in the processof connecting them to make a food web. This is similar to Extension 2 on p. 649 of the textbook. The book does not provide any information on direct and indirect relationships in the food chain, nor does it explain what happens to other organisms in the food chain when an organism is added to or removed from the food chain. I would provide the students with a vivid experience to illustrate this point. I would extend the lesson plan linked below, which is a student activity in which students build a Great Lakes Food Web. I would actually have the students add in the sea lamprey and then adjust the food web accordingly. As described in the lesson plan, I would have the students remove an organism and then describe the consequences for the food web.