Lesson Title: Plant and Animal Cells: How do they differ? Grade level: 6th PREREADING: MOTIVATION: Do you think that we depend on plants to survive? Why or why not? List ways that you think we depend on plants for survival. Food, clothing, building materials, for oxygen. Do you think a plant needs humans to survive? Why or why not? Write your predictions down in your science journal. Students might write that they don't think plants needs humans to survive since they make their own food. They also might say that plants DO need humans since humans need plants. We will be finding the answers to these questions. II. Prior Knowledge: As we discussed in lesson 1, there can be many differences between organisms. Some live in the air, others live on land or under the ground. There are more than 30 million different kinds of living things that live on this Earth. I will be asking you some questions now and you need to write these questions, as well as the answers we come up with in your science journals. I will write the answers on the white board. What is every living thing made up of? Cells What is the definition of an organelle? It is the name of a structure found in a cell. Can you name some of the organelles that an animal cell contains? Write all of the organelles down that you can think of in your Science Journal. The teacher gives the students some time to write, then they will share what they wrote. Ribosomes, mitochondria, cytoplasm, nucleus, endoplasmic reticulum, cell membrane, vacuole Students might need some review of this material even though it was covered in the previous lesson. This will give the teacher a chance to see what information they have retained and if a re-teaching will be necessary. Write down every difference you can think of between plants and animals in you science journals. The teacher gives the students some time to write. What are some of the things you came up with? plants are usually green, animals eat other animals or plants, plants are usually green (only some animals are green), plants do not make noises, animals can not make their own food inside of them
III. Purpose Today we will read to not only find out if plants need animals to survive, but we will read in order to answer whether plant and animal cells are the same. We will read in our science books on page A20, which is still part of the chapter entitled, "Structure and Function of Cells." The section we are reading is set-up as a compare and contrast text and shows the similarities and differences between plant and animal cells. Remember that it is helpful to first skim the reading, paying special attention to the headings so you know what type of information will be included in each section.
IV. Strategy instruction: Prediction Guide (type if anticipation guide from Reading Strategy Chart) We will be using a Prediction Guide. The purpose of this will be to make predictions about whether we agree or do not agree with statements about cells and to make comparisons between your own opinions and what the author thinks. The following are the steps that you should follow when using this Prediction Guide.
MODEL: I might see a statement such as the following: The cell theory states that the cell is the basic unit of all living organisms and only living cells can produce new living cells. I would then decide that I would agree with this statement since I know that dead cells cannot produce living cells and that all organisms are made up of cells. GUIDED PRACTICE: Let's look at this statement together. Sunlight is absorbed by plants and used for food. Now, what do we know about how plants get food? They get it from the sun. Correct. And it makes sense that the plant would have to absorb the sunlight in order to use it for food. So, do we agree or disagree? Agree. Then we would mark a plus (+) in the "me" column. The first row would look like this so far:
INDEPENDENT PRACTICE: Now, finish the rest of the statements on your own. Only do steps 1 and 2 at this time. 1. Read each statement. 2. Place a plus (+) in the "Me" column if you agree and a minus (-) if you do not agree. We will go back to the rest later (students will have their own form to fill out). The following is an example of what a student's "Anticipation Guide" should look like at this point:
NOTE: "Anticipation Guides" should not be graded based on the "me" column. The teacher should focus on the accuracy of the "author" column and whether the students corrected the statements that were not accurate. DURING READING: Cooney, T. (Ed.). (2000). Scott Foresman science. (Grade 6, pp. A20-A24) Glenview, Illinois: Scott Foresman. Readability: 7.6 using the Flesch-Kincaid; Some of the content of this science lesson requires using vocabulary that may seem to be very complex. This would explain the slight increase in grade level readability. Most of the names of the organelles of plant and animal cells are not typically used in the everyday language of a 6th grader, yet they have been familiarized with these words, bringing the readability to a more appropriate level. The drawbacks of using a readability formula are well-documented, so the cuing system and other readability factors should be considered. Syntactically, the sentences are not complex enough that would make an average 6th grader confused. Although there are some compound sentences, the author does a thorough job of keeping the sentences straight-forward and manageable to comprehend. There are pictorial elements present that also allow for comprehension. The picture of the inside of a plant cell illustrates the shapes and sizes of the organelles in relation to each other, allowing the reader to differentiate between each one. The text makes reference to previous lessons to fit the new information into the students' schema, also creating interest in the topic. This text is appropriate for students at the 6th grade level. Differentiation: Most of the students should be able to read the text. For advanced readers, they can read the following text: Kaskel, A. (1988). Biology: An everyday experience. (pp. 29-33) Columbus, Ohio: Merrill Publishing Company. Readability: 8.4 Students who are struggling with the concept of plant and animal cells and their differences should use this worksheet format from this link in order to organize their information. http://www.teach-nology.com/worksheets/science/cell/1/ Students who seem to grasp the concept of plant and animal cells very well and need to be challenged should use this link to go to a site that shows some more complicated illustrations and gives more in depth descriptions of the different organelles in a cell. http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/cells.htm V. Text Structure: Expository text- 6th grade Science Textbook
VI. Vocabulary Chloroplasts are organelles found in plant cells that make sugar using carbon dioxide, water, and energy from the sunlight. Chlorophyll is the green substance that is found in chloroplasts that traps energy from sunlight. Photosynthesis means "putting together with light." During photosynthesis, oxygen is also formed and released by the plant into the atmosphere. The students would have already learned terms such as nucleus , chromosome , organelle , mitochondria , vacuole , endoplasmic reticulum , and ribosome that are important for understanding the material in the lesson. VII. Content If you are ever at the point where you are not comprehending
your reading, what do you need to do? Stop. Ask, what is it that
I don't understand? Ask, what can I do to understand this better? Should
I reread? Should I look ahead? Should I talk with a peer? Should I
ask the teacher? The students will need to refer back to what they learned about organelles in the previous lesson. The ribosomes produce proteins for the cell. The mitochondria release the energy stored in food. The cytoplasm fills most of the cell outside the nucleus. Organelles float in the cytoplast. The nucleus is the control center of the cell. The endoplasmic reticulum moves materials throughout the cell. The cell membrane holds the parts of the cell together and controls the movement of materials into and out of the cell. The vacuoles store water, nutrients, and wastes.
AFTER READING: VIII. Questioning Let's finish filling out our chart. Look up at the board at our steps. Remember, you should now place a plus (+) if the author did agree with the statement and a minus (-) if the author did not agree. These pluses and minuses should be placed in the "author column." Next, you should compare your projections with the author's statements. Finally, change all the minus statements in the "author" column so that they agree with the textbook and write down the page number where you found the information. I will show you the first example from my chart I have filled out. The following is an example of what a completed chart might look like.
Now, let's go through and discuss how you came to your conclusions. Does anyone remember the four different Question-Answer Relationships? "right there," "think and search," "author and me," and "on your own." I will change the above statements to question form and also ask you some other questions. Remember that after answering the question, you should state what type of question-answer relationship it was (right there, think and search, author and me, or on your own). The following questions will be in a discussion type format with the teacher being the facilitator. 1. Are plants and animals exactly the same? No. Plant and animal cells are similar, but not exactly the same. This answer is right there since the text says, "nearly all animal and plant cells contain cell membranes, nuclei, cytoplasm, and other organelles, but they differ in some ways too." 2. Do humans and almost all other life on Earth depend on the process of photosynthesis? Yes. This answer is think and search since the text says, "It is a process on which you and almost all life on earth depend.." but the reader has to search farther to find what "it" stands for. 3. What would happen if we didn't have this process? There would not be life on earth. This answer is on my own since the answer came from my own brain. 4. Do both plant and animal cells shrink when they do not have enough water? Yes. This answer is right there since the text says, "Animal cells shrink too, but not as much as plant cells do." 5. When leaves change colors in the fall, do they lose their chlorophyll? Yes. Temperatures drop, breaking down the chlorophyll and exposing other colors. Normally the green of the chlorophyll hides the other colors. This answer is author and me since the reader needed to use his/her own prior knowledge AND what the author had to say. 6. Is sunlight absorbed by plants and used for food? Yes. This answer is think and search since there are bits and pieces of the answer throughout the text. The text says in one area, "...this energy is absorbed by green plants" and in another area, "What a plant can do then is change light energy into chemical energy, which is stored in glucose." 7. Is there chlorophyll in animal cells that trap energy from the sun to make sugars? No. This answer is right there since the text says, "chlorophyll traps energy from the sun to make sugars. Animal cells can't do that. 8. Does photosynthesis mean to take a picture in order to examine an object? No. This answer is right there since the text says, "Photosynthesis means 'putting together with light." 9. Does chlorophyll contain chloroplasts? No. Chloroplasts contain chlorophyll. This answer is right there since the text says, "...you have seen the presence-and disappearance-of chlorophyll in chloroplasts." 10. Does a plant cell have a cell membrane AND a cell wall? Yes. This answer is right there since the text says, "A plant cell has a cell wall in addition to a cell membrane." 12. Do plants and animals have a nucleus? Yes. This answer is right there since the text says that all plant and animal cells have nuclei. 13. Why do you think it is important for both plant and animal cells to have a nucleus? Because the nucleus is the control center of the cell. Like the brain. This is answer is author and me since the student would need to use prior knowledge and the current text to answer this question. 13. What is the difference between photosynthesis and respiration? Photosynthesis uses energy to combine carbon dioxide and water to produce glucose and oxygen. Respiration uses oxygen to release the energy stored in glucose and produces carbon dioxide and water. This answer is author and me since the student would need to use the text and his/her prior knowledge about respiration to answer. 14. Let's think back to the question we asked at the beginning of the class period. Do you think a plant needs humans to survive? No. Plants need sunlight and water to survive, but they do not need humans. They rely on the process of photosynthesis to make food. This answer is think and search since all the information is in the reading, the student must put some pieces together. ***It is essential that students understand the similarities and differences between plant and animal cells. In order to make sure that students comprehend this, the teacher will guide them in understanding the differences. Students, do you remember looking at this website that shows what an animal cell looks like under a microscope? Yes. The teacher brings the website up again to refresh the students' memories. http://sciweb.hfcc.net/Biology/jacobs/bio131/cells/images/cheek1.jpg Now I am going to show you what a plant cell looks like under the microscope. The teacher brings up the website: http://grandpacliff.com/Plants/Img-Plants/elodea-plasts.jpg I want everyone to write in your science journals their answer to this next question. Do NOT blurt the answer out. What do you think these lines or boxes are? The teacher gives the students time to write their answers in their journals. Can someone share what they wrote? cell walls This answer is right there since it was in the students text. Animal cells also have cell walls, right? No. What else do you notice in this picture that is different from the animal cell? the green balls. Write the next answer in your science journal What do you think these green balls are? chloroplasts. Do animal cells have chloroplasts? No. Why do you think they do NOT have chloroplasts? The process of photosynthesis does not occur in animal cells since animals get their energy from food, not the sunlight, like plants. IX. Writing to Learn Students have been writing throughout the lesson, but this will be their chance to make some conclusions and summaries of the information they learned in this lesson. The teacher will remind the students that even though their writing will not necessarily be graded on grammar, punctuation, and spelling standards, they should still keep proper writing mechanics in mind. In order to set the students up for success, the teacher will require the students to refer back to the Venn Diagram that they helped to construct at the beginning of the lesson. The students should write two short essays (at least one written page total) where they answer the following questions: 1. How do plant cells differ from animal cells? (should include at least 3 differences) 2. How are plants important to all living things? . The students will turn this assignment in next class period. The following is an example of what a student's finished assigment might contain: There are some big differences between plant cells and animal cells. One main difference is that plant cells are usually larger than animal cells. Both plant cells and animal cells have vacuoles, but plant cells have one large vacuole that is located at the center of the cell. Animal cells have several small vacuoles. When plants are wilted, it can mean that they do not have enough water. If the plant is given water, the vacuoles in its cells get filled with water, making the plant more firm. Plant cells have cell walls and cell membranes and animal cells only have cell membranes. Plant cells have chloroplasts that contain chlorophyll. Animal cells do not. Plant cells rely on photosynthesis to make food. Plants are important to all living things. Plants release oxygen into the air so animals can breath. Plants also provide food to animals. X. Closure Directions for independent practice of strategy: We might be using the Anticipation Guide strategy with other readings. Remember that the procedure for the strategy will always stay the same. Does anyone remember the steps? read the statements, place a "+" in the "Me" column if you agree or a "-" if you do not agree, read the assigned pages, read the statements again and place a "+" in the "Author" column if the author agreed or a "-" if the author did not agree, change all the "-" statements in the "Author" column so they agree with the text, and write down the page numbers where you found the information. Correct! The only part that will change next time is the page numbers and statements. Remember that our purpose was to not only find out if plants need animals to survive, but whether plant and animal cells are the same. Do you feel that we fulfilled our purpose today? Yes. We found out that even though plants and animal cells are similar, they are not exactly the same. What are the major differences? Animal cells do not have chloroplasts and plant cells do. Since animal cells do not have chloroplasts, photosynthesis does not occur in animal cells. Plant cells can make their own food when they get energy from the sun. Animal cells have to get energy and food from other organisms. Plant cells have cells walls in addition to cell membranes. Metacognitive Reflection: How well do you think our anticipation guide worked? It worked well. Why do you think it worked so well? We were able to think about what we learned in the last lesson to help us understand the new information.
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