Lesson Plan Template: General Lesson Plan
Learning Objectives: What will students know and be able to do as a result of this lesson?
Students will be able to test a liquid for photosynthetic products using pH and dissolved oxygen analysis.
Students will be able to explain the light-dependent and light-independent cycles of photosynthesis.
Prior Knowledge: What prior knowledge should students have for this lesson?
Students should have a general background knowledge in photosynthesis e.g. 6H2O + 6CO2 = C6H12O6 + 6O2.
Guiding Questions: What are the guiding questions for this lesson?
How can we tell/test that photosynthesis is happening? What are the limitations to our tests?
Introduction: How will the teacher introduce the lesson to the students?
The lesson should start with lab set-up. Preferably, this is just setting up the physical elements of the lab - Have students take notes on set-up and revisit the set-up/experimental design as the lesson progresses.
Investigate: What question(s) will students be investigating? What process will students follow to collect information that can be used to answer the question(s)?
Students will be investigating photosynthetic products and the process of photosynthesis.
Lab equipment required: 4 - 250mL beakers/group; 4 small (must fit inside beaker) clear funnels/group; 4 test tubes/group; 4 Elodea cuttings/group (3 of the same size 1 significantly larger or smaller - 2X or 1/2);
Option equipment: dissolved O2 sensor; pH indicator (for example: Vernier pH probe or bromothylmol blue); scale
Elodea is an aquatic plant - submerge the Elodea in water in the 250 mL beaker; place the funnel (clear funnel) over the Elodea in the water; invert a test-tube full of water over the submerged elodea/funnel combination.
This set up will allow students to measure gaseous product (trapped in test-tube) by how much water it displaced. The students can also measure dissolved O2 with the dissolved O2 probe and they can measure pH with teacher selected indicator (Vernier data logger allows you to store, track the data). This will allow students to determine the source of CO2 for the photosynthetic reaction and the changes in water chemistry.
With 4 set-ups, students can have full-light v. partial light; and large v. small biomass.
Analyze: How will students organize and interpret the data collected during the investigation?
Students will track water pH, volume of gaseous product for the following conditions: full-light v. partial light; and large v. small biomass.
pH will be affected by CO2 concentration in the water - higher CO2 correlates with more acidic conditions. And difference in conditions represents a difference in rate of photosynthesis. Full light>partial light; large biomass>small biomass.
Students will be asked to predict measurable changes in the lab set-up.
Closure: What will the teacher do to bring the lesson to a close? How will the students make sense of the investigation?
The intent of this lab is for students to be able to predict outcomes of the lab based on class presentation of photosynthesis/cellular respiration. A good practice is to discuss the variation in group, classroom (aggregate) data - if this is done with multiple classes a discussion of replication studies is also encouraged. It is also appropriate to discuss (acceptable) data ranges for different investigations e.g. cell biology, genetics, ecology.
In addition to learning the processes of photosynthesis, students will be able to identify ways of testing for photosynthetic products - they will also identify the limitations of the tests performed in class and suggest other ways they could test whether photosynthesis is happening.
Teachers can extend this into a graded lab in numerous ways:
1) Lab notebook check showing evidence of - group and class data; explanation of variances in data (group and classroom); explanation of changes in pH and dissolved oxygen; etc.
2) Students can also be asked to create a formalized lab report with descriptions of light-dependent and light-independent cycles of photosynthesis and how the evidence collected supports or rejects these concepts and other recommended means of testing for light-dependent and light-independent cycles of photosynthesis.
Teacher Note: pH should become more basic in this process because the plant bio-mass will use CO2 in respiration - as part of the reaction product, students should also see an increase in dissolved oxygen content. The light-independent cycle will still use CO2 resulting in a more basic pH reading, however, without the complementary light-dependent cycle, ATP and NADPH2 are not replenished which means readings for dissolved oxygen will be lower and the pH should not be as basic as those also exposed to light.
This is primarily a lab activity investigating the products of photosynthesis. It will ultimately span a few days but only insofar as there will be set up one day and students will take a few minutes to check outcomes over the following days.
During "down-time" of the lab activity it is appropriate to teach about the associated scientific processes: photosynthesis; respiration; light-dependent and light-independent cycle (Calvin Cycle). During the lesson, the teacher is encouraged to ask questions about energy processes and relating the questions to the lab set-up will encourage students to think about the connection to the experiment and the sampling they are doing. The teacher can have students discuss predictions in their lab groups, then lead into a class discussion about predicted results for the various conditions.
Feedback to Students
Initially, students will be given support during lab set-up.
Data will be collected as a class data set - after lab-group discussion, teacher will help facilitate consensus view of photosynthetic process and products based on lecture material.