Title: Photosynthesis Phun Author: Jean Marie Buschur Overview: An activity using Skittles to show how the photosynthesis reaction balances. Suggested grade level(s): 7-10 Concepts covered: Photosynthesis, Cellular Respiration, Balanced Equations, Conservation of Mass, Chemical Formulas and Names Standards: Based on South Carolina 7 th grade standards. III. Earth Science Unit of Study: Ecology The Abiotic Environment A. Structure of the Earth System 6. For ecosystems, the major source of energy is sunlight. Energy entering ecosystems as sunlight is transferred by producers into chemical energy through photosynthesis. That energy then passes from organism to organism in food webs. a. Describe how sunlight, through photosynthesis, is transferred by producers into chemical energy. Length of lesson: 90 minutes (7 th grade) Materials required: Student worksheet Student cut-out sheet Papertowels Skittles separated by color and numbered (36) Dixie cups for the skittles Scissors Lesson Format Phase I. Engage Is what goes in really what goes out? When cells take in materials to make food, do they loss anything in the process? Write the equation for photosynthesis using the students input. Explain how the stoichiometry works if not covered before. Phase II. Explore Using the student activity sheet on page 2 follow through the steps to build the photosynthesis equation. Page 1 of 7
A key follows the student sheet. Page 2 of 7
Photosynthesis Phun Name: Date: Bell: Photosynthesis is the chemical reaction in which plants and other organisms make food for their cells. The food is made in the form of glucose (C 6 H 12 O 6 ) which is a type of sugar. This reaction occurs in small compartments of each cell called the chloroplasts. 1. Write the equation for photosynthesis here: 2. For the reactant side of the equation write each chemical formula, the name of the 3. What is the source of energy for this equation to take place? 4. For the product side of the equation write each chemical formula, the name of the 5. Write the names and symbols of the three elements used in this equation and color you will make this element (red, orange, purple, green, or yellow). Symbol Name Color = = = = = = We are now going to build this equation. Each piece will represent one element. First, cut out and arrange the pieces of the equation on your table. Under each piece lay a piece of paper towel. Next, arrange your skittles to form the molecules in each step of the reaction. Once you have your pieces laid out ask a teacher to check your work. Page 3 of 7
6. Fill in the following chart with the numbers of each element based on your model in front of you. Number of Carbons Number of Hydrogens Number of Oxygens Total numbers (add up first 3 columns) Reactants Products Check with the teacher to make sure you have this filled in correctly. 7. The number of elements on the side of the reactants is. The number of elements on the side of the products is. What conclusion can you draw from this?. When the numbers on an equation on both sides are equal this is called the Law of Conservation of Matter. 8. Why do cells do photosynthesis?. 9. What molecule represents food that is made in photosynthesis?. 10. List the reactants. 11. List the products. Page 4 of 7
Photosynthesis Phun Key Name: Key Date: Bell: Photosynthesis is the chemical reaction in which plants and other organisms make food for their cells. The food is made in the form of glucose (C 6 H 12 O 6 ) which is a type of sugar. This reaction occurs in small compartments of each cell called the chloroplasts. 1. Write the equation for photosynthesis here: 6H 2 O + 6CO 2 + light energy C 6 H 12 O 6 + 6O 2 * The students should be able to do # s 2-4 on their own. 2. For the reactant side of the equation write each chemical formula, the name of the H 2 O = Water 6 CO 2 = Carbon Dioxide 6 3. What is the source of energy for this equation to take place? sunlight 4. For the product side of the equation write each chemical formula, the name of the C 6 H 12 O 6 = Glucose 1 O 2 = Oxygen 6 * The students will get three colors of Skittles, they get to chose what to make each color. 5. Write the names and symbols of the three elements used in this equation and color you will make this element (red, orange, purple, green, or yellow). Symbol Name Color C = Carbon = H = Hydrogen = O = Oxygen = We are now going to build this equation. Each piece will represent one element. First, cut out and arrange the pieces of the equation on your table. Under each piece lay a piece of paper towel. Page 5 of 7
* Their set-up should have the symbols above the papertowels laid out in the correct order. Next, arrange your skittles to form the molecules in each step of the reaction. Once you have your pieces laid out ask a teacher to check your work. * It is easiest to spot check the Skittles laid out as you walk past. They should have used all of one color (the oxygens) but the rest of the colors should not be used up. I kept these extras and used them in another class. 6. Fill in the following chart with the numbers of each element based on your model in front of you. Reactants Number of Carbons 6 6 Number of Hydrogens 12 12 Number of Oxygens 18 18 Total numbers (add up 36 36 first 3 columns) Products Check with the teacher to make sure you have this filled in correctly. 7. The number of elements on the side of the reactants is _36. The number of elements on the side of the products is 36. What conclusion can you draw from this? Equal on both sides, what went in came out, etc.. When the numbers on an equation on both sides are equal this is called the Law of Conservation of Matter. 8. Why do cells do photosynthesis? _to make food. 9. What molecule represents food that is made in photosynthesis? glucose C 6 H 12 O 6. 10. List the reactants. _water H 2 O, carbon dioxide CO 2 11. List the products. glucose C 6 H 12 O 6, oxygen 6O 2 Page 6 of 7
Phase III. Explain As the students finish the questions and had their set-up checked, I allowed them to eat the Skittles. Once they had finished the questions I went over them and explained why the reaction balanced.. Phase IV. Elaborate Ask the students how the photosynthesis reaction relates to cellular respiration. Have the students talk through how cellular respiration is the reverse of photosynthesis. If needed they can move around the pieces on their table and see how cellular respiration is the exact opposite of photosynthesis. Phase V. Evaluate A sample rubric. CATEGORY 4 3 2 1 Worksheet All variables are clearly described with all relevant details. Professional looking and accurate the data in tables. Tables and are labeled and titled. All variables are clearly described with most relevant details. Accurate the data in tables. tables are labeled and titled. Most variables are clearly described with most relevant details. Tables are not accurate the data. Variables are not described OR the majority lack sufficient detail. No tables are presented. Activity Professional looking and accurate the equation. Accurate the equation. The model was not an accurate the equation. No model are presented. Participation Played an active role in the class discussion of the activity. Participated in or actively listened to the class discussion. Listened somewhat to the discussion. No attention or participation in the discussion. Page 7 of 7