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Lesson Plans > Science > Grades 6 - 8 > Photosynthesis
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Kinesthetic Learner
Kinesthetic Learner
Visual Learner
Visual Learner
Auditory Learner
Auditory Learner
Technology Integration
Technology Integration

Photosynthesis

Understand the role of plant pigments in photosynthesis

 

Grade Level: 6-8

Concept: Understand the role of plant pigments, such as chlorophyll, in photosynthesis

Estimated Duration: 90 minutes
 
Objectives
Students will be able to:
  • relate the basic principles of photosynthesis
  • use paper chromatography to evaluate a hypothesis regarding plant pigments
  • understand the role of chlorophyll and other pigments in photosynthesis
Materials
Handouts with an assortment of images relating to photosynthesis
Leaves collected from a variety deciduous trees, labeled according to each tree and placed in plastic bags
Glass jars
Rubbing alcohol
Scissors
Shallow tray with hot water
Plastic spoons
Coffee filters
 
Differentiation Strategies
These strategies are used to meet the varied needs of all learners:
  • for various grade levels Varying academic levels: uses mixed-ability groups allow students to learn from one another, small and whole group participation
  • for visual learnersVisual learners: incorporates images related to photosynthesis, written guidelines, and journal writing
  • for auditory learners Auditory learners: uses discussion and direct inquiry to review concepts related to photosynthesis and discuss results of experiment
  • for kinesthetic learners Kinesthetic learners: engages students in an experiment to prove or disprove their hypotheses
Key Vocabulary
photosynthesis
chromatography
chlorophyll
chloroplast
chemical reaction
 
Procedures
Warm Up
  • for various grade levels Pair stronger academic students with challenged students.
  • for visual learners  Distribute to pairs of student an image related to photosynthesis (e.g., an anatomy of a leaf, the formula of the overall chemical reaction, a diagram of a chloroplast). Make sure to have an assortment of images.
  • for auditory learners Have them turn to their partner and discuss what information is conveyed in the image regarding photosynthesis.
  • Ask students to present their image to the class, how the image relates to photosynthesis, and what information the image provides.
Direct Instruction
  • for auditory learners Ask the class to think about why the leaves of some trees change color in the fall. Ask them whether they believe that the red, yellow, and orange colors are present in the leaf when the leaf is green, or whether these colors are formed in the leaf only during the fall.
  • Ask students to formulate a hypothesis regarding whether the red, yellow, or orange pigments are present in green leaves and write it down on paper or in their science journals. Have students raise their hand to indicate which hypothesis they formed.
  • Review the principles of paper chromatography. Ask students how they could use paper chromatography to find out whether the red, yellow, or orange pigments are present in the green leaf.
  • for visual learners Distribute instructions for the chromatography lab. Include the following points:
  • Remove leaves from plastic bag and cut into small pieces.
  • Place pieces on the bottom of jar.
  • Label jar with your name and the name of the leaf.
  • Cover pieces with rubbing alcohol and grind with plastic spoon until liquid turns green.
  • Place in shallow pan filled with hot water and place lid loosely over jar. (Teacher should refill if water cools down.)
  • Mix every 5-10 minutes during the next 30 minutes.
  • Cut coffee filter into long strips.
  • After 30 minutes, the liquid should be dark. Place the coffee filter strip in the jar so that it touches the liquid and tape it to the side of the jar.
  • Leave for approximately 45 minutes. Then check for separation of colors.
  • Invite two students to model the initial steps. Make sure that they cut the leaves up into very small pieces.
Practice
  • for various grade levels  Students can perform this lab individually or in pairs. When grouping students for the lab, pair up ELL students with English-proficient students or those with stronger and weaker organizational skills.
  • for kinesthetic learners Have students carry out the lab, and then label their coffee filter and tape it to the poster board.
Assessment
  • for visual learners Ask students to summarize their results on paper or in their science journals.
  • Looking at the filters, ask students to return to their hypothesis, and formulate a conclusion on paper or in their journals.
  • for auditory learners Ask students to describe their results and share their conclusions.
Closure
  • Reading/writing learners: If Internet access is available, ask groups of students to research one of the following topics:
  • the identity and purpose yellow and orange colors they observed on the filters;
  • the identity and purpose of the red and purple pigments that only appear in the fall; or
  • what happens to the green pigments in the fall.
  • Reading/writing learners: If Internet access is not available, distribute a paragraph or two discussing these three topics. Ask students to explain the identity and purpose of the different pigments and what happens to green pigments in the fall.
  • Extension: Have students speculate why some coffee filters only showed green pigment. Is alcohol not the best solvent to use with plant pigments? Do some plants not have the carotenes and xanthophyll? What kind of plants might not have these pigments?
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