By breaking down food chains in terms of trophic levels, biomass, energy, organism abundance - and oddly enough, popcorn in a concluding lab report! - this lesson supplements the traditional understanding of food chains' predator-prey functioning. Adding to our vocabulary-based reading strategy for our class and homework readings, we pinpointed and defined the purpose of several main text features - headings, captions, bold vocabulary, figures, and key symbols - found in our science textbook as the first of two nonfiction-specific reading strategies to be used in this unit to navigate the scientific language of our textbook and future popular science articles. Drawing first from the text feature in the English classroom's specific copy of "A Sound of Thunder" - pull quotes - to introduce the concept and important of text features, we worked through the ones that dominated our science textbook and immediately applied them when deciding how best to understand the ecological pyramids described on a two-page spread in your homework textbook reading.
Reading Strategy Mini-Lesson: Text Features
Cross-Curricular Connection Yesterday in your English class, you started Ray Bradbury's "A Sound of Thunder" and examined Eckels's attitude toward time travel. Take a look back at your copy of the short story. Just by skimming, how can you immediately gauge the protagonist's opinion on time travel? Look at the third page (p. 74). What jumps out at you? There is an enlarged quote from the text in the middle of the page. It is a text feature known as a "PULL QUOTE." Predict why that specific line was enlarged and spotlighted. Based on how you spent yesterday's English lesson examining Eckels's attitude about time travel and TimeSafari, Inc.'s role in it, it was important information. So the layout of the text scaffolded you to that awareness. Similarly, in nonfiction texts - like your science textbook - there are particular text features that make the identification of important information easier and clearer. |
Reading Strategy Mini-Lesson: Comprehension
Nonfiction Text Features After discussing the purpose of the "PULL QUOTES" in your specific copy of "A Sound of Thunder" and prompting you to tune in to them as you continue reading the short story, we moved on to several main text features in our science textbook:
For each of the five highlighted text features, we referred to our textbook (Ch. 3-2 "Energy Flow," pp. 67-73) to describe their appearance and location in the text. Then in a Think-Pair-Share activity, we discussed their purpose in the text. Individually and then collaboratively, we brainstormed their benefit to us as readers. How do they help us? What kind of information do they highlight? How and when should we use them while reading? Which should be zoom in on when just skimming/scanning the text for specific information (i.e. examples of the content, important terminology, big ideas, visual reinforcement of written material, etc.)? |
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TROPHIC LEVELS |
Text Feature Application:
Food Chain & Ecological Pyramid Graphic Organizer To immediately apply our new knowledge of text features, we navigated them to understand and diagram ecological pyramids (Ch. 3-2 "Energy Flow," p. 72-73). With all discussed text features embedded within the two textbook pages on which the ecological pyramids are discussed, we brainstormed how to proceed with our reading. Which ones do we let our eyes jump to first? Which should be rely on for that initial understanding? After filling in the graphic organizer for the food chain trophic levels, energy pyramid, the biomass pyramid, and pyramid of numbers, we each came up with a food chain in the provided boxes, either labeling the boxes or drawing pictures of the organisms. We discussed the correct way to draw the arrows in a food chain - and provided the reason for their direction. Then, we switched with a partner, and we had to label each organism with its appropriate trophic level and draw a sun next to the the level with the most energy. |
IMPORTANT REMINDER WHEN DRAWING FOOD CHAINS:
In a food chain, arrows point in the direction of energy flow, so they DO NOT point from predator to prey.
Food Chain: A series of predator-prey relationships in which organisms transfer energy by eating and being eaten.
Biomass Pyramid: The total amount of living tissue within a given trophic level decreases as one progresses higher in the food chain.
Pyramid of Numbers: The total number of individuals at each trophic level in an ecosystem. Not confined to a pyramid shape like the others.
Energy Pyramid: The total amount of energy at each trophic level decreases as one progresses higher in the food chain, due to how organisms only receive 10% of the energy from their food.
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Trophic Level: Each step in a food chain.
Producer (Autotroph): Organisms - like plants, algae, and bacteria - that covert solar/chemical energy into food.
Consumer (Heterotroph): Organisms that cannot harness energy directly from the physical environment, so they acquire energy by eating other organisms.
Apex Predator: a
predator with few or no predators of their own, so they lie at the top of their
food chain. They occupy the highest tropic level, which is usually greater than
the fourth.
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LAB REPORT:
Popcorn Food Chain Energy Flow In the first lab of the unit, we worked with popcorn and electronic scales to calculate and measure the exact amount of energy that would be transferred to each successive trophic level in food chain. With the popcorn being our energy source, we weighed and broke down the fluffy kernels to meet our calculated energy totals that would actually be at each level based on our starting total (the weight provided on the popcorn bag). Bags of SmartFood popcorn for energy, various plastic dishes for each trophic level, and an electronic scale was distributed to each group of two to three students. If absent, you will need to attend after-school extra help to make up this lab report. We referred to the textbook pages that we examined and diagrammed in the beginning portion of the lesson (pp. 72-73; and the relevant portions are also excerpted on the lab's instruction sheet), so we used our class worksheets as reference sheets, as well. With the key understanding that 10% of energy is transferred to each successive trophic level because most is lost as heat to the environment or as fuel for the life processes of the original organism (i.e. respiration, digestion, etc.), we worked to record our purpose, our materials, our steps, our results, and our conclusion on individual lab reports. |
Due to the absence of a specific teacher-given procedure for you to devise a method to calculate accurate energy totals at each trophic level (that's part of the challenge!), keep in mind several basic, but key formulas we've worked with before in previous labs. However, please know that the teacher is always available as a a resource, as well.
KEY FORMULAS:
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