Applying Standards Based Constructivism:
A Two-Step Guide for Motivating Students
Photosynthesis and Respiration

Popular Name: Photosynthesis and Respiration
Grade Level: 10th Grade
Discipline: Living Environment (Biology)

Standards:

Students will use mathematical analysis, scientific inquiry, and engineering design, as appropriate, to pose questions, seek answers, and develop solutions.
Students will understand that organisms maintain a dynamic equilibrium that sustains life.

Learning Objectives:
Students will:
Be able to write a report based on an experiment they developed and perform.
(The experiment is to prove the scientific principle regarding carbon dioxide’s contribution to both photosynthesis and respiration.)

EXPLORATORY PHASE:

Students as a whole class, conduct a test involving the relationship between respiration and carbon dioxide.
Students use textbook-based information to prepare to explain the relationship between respiration and photosynthesis.

DISCOVERY PHASE:

Performance Task:
Students will develop and perform an experiment to prove each of the following statements:

Plants carry on photosynthesis and use carbon dioxide.
Plants carry on respiration and release carbon dioxide.

(The task will include writing an experiment report that includes labeling diagrams.)

Photosynthesis and Respiration

Popular Name: Photosynthesis and Respiration
Grade Level: 10th Grade
Discipline: Living Environment (Biology)

Standards and Performance Indicators Context

MST Standard 1

Students will use mathematical analysis, scientific inquiry, and engineering design, as appropriate, to pose questions, seek answers, and develop solutions.

MST Standard 4: Science

Students will understand and apply scientific concepts, principles, and theories pertaining to the physical setting and living environment and recognize the historic development of ideas in science.

Key Idea 5:

Organisms maintain a dynamic equilibrium that sustains life.

Performance Indicator 5.1:

Explain the basic biochemical processes in living organisms and their importance in maintaining dynamic equilibrium.

Core Curriculum Outline Connection

Major Understandings

Plant cells and some one-celled organisms contain chloroplasts, the site of photosynthesis. The process of photosynthesis uses solar energy to combine the inorganic molecules carbon dioxide and water into energy-rich compounds and release oxygen to the environment.
In all organisms, the energy stored in organic molecules may be released during cellular respiration. This energy is temporarily stored in ATP molecules. In many organisms, the process of cellular respiration is concluded in mitochondria, in which ATP is produced more efficiently, oxygen is used, and carbon dioxide and water are released as wastes.

Learning Objectives (which will become the dimensions of the assessment’s rubric.)
Students will be able to:

Write a report based on an experiment they develop and perform.
Prove the scientific principle regarding carbon dioxide’s contribution to both photosynthesis and respiration in plants.

EXPLORATORY PHASE
(Estimated time: one period of 45 minutes)

1. As a whole class demonstration:

Measure about 50 ml of bromothymol blue into two Erlenmeyer flasks.
Select two volunteers based on similar size and gender.
Have one student run in place for a minute and have one sit quietly.
Put a straw into two flasks and have the two volunteer students exhale into their flasks until the bromothymol blue turns light green or yellow.
Make sure they face their classmates while they blow into the flasks. (The students notice that the solution in the flask of the student who ran turns color faster.)
Write “notes” on the board regarding their observations of bromothymol blue and the color it is when CO2 is present or absent. (When it is absent, the fluid is blue, with little CO2 it starts to turn green, with higher levels of CO2, it is yellow.)

2. Ask students what happened and why? Discussion should include the color change of the bromothymol blue and the exhaling of carbon dioxide.
3. Ask students what processes they are familiar with that involve carbon dioxide. (The teacher may have to lead the students to conclude that the processes are photosynthesis and respiration.) Assign half the students to find out about photosynthesis and the other half to find out about respiration.
4. Students are directed to find out: the equation that summarizes the process, where it occurs in the cell and what types of organisms it occurs in. Students are told that each of them has to know the information, as they will explain it to someone on the other side of the room. They have 15 minutes to find the information and write it down. Students use their textbooks.

Spontaneous Intervention

5. As students work, the teacher walks around and intervenes through redirection when necessary.
6. After students have worked for 15 minutes, determine if they need more time or not. If more time is needed, allow for it. To make this determination:

Listen to what the students are taking about and read what they have written.
Ask questions regarding the task and intervene when groups get stuck.
While the students are required to find the information, spontaneous interventions may be necessary to move them along. These interventions may include directing the students to the pages in the textbook where the information can be found.

7. Bring all the groups working on one of the topics together to compare notes and to allow the teacher to monitor the correctness of the information. This is included in the 15 minutes.
8. After the students have completed this part of the Exploratory Phase, pair them so that two students from one side of the room are explaining their process (photosynthesis or respiration) to two students from the other side of the room and vise versa. They will have 6 minutes to explain their information. Working in groups of 4 will result in fewer mistakes. The teacher walks around the room and listens. (Have the students who looked up photosynthesis go first. This will avoid the teacher from getting confused regarding which topic is being discussed.)
9. When they are finished, students report out and the teacher writes the equations on the board. The process is as follows:

Ask for volunteers.
The rest of the class checks for accuracy.
The teacher writes on the board what the volunteers are reporting out.
The teacher might select groups if she has heard them making a point she wishes to stress.
The teacher asks for agreement from the class. This requires student engagement and highlights main points and misunderstandings/inaccuracies.

10. In pairs, have students compare the equations. What do they notice? (The equations are opposite.) The process is as follows:

The teacher “works the room”, listening and watching.
Students are directed to use a “two-foot voice” so they don’t “give away answers.”
Students stay engaged because they like being able to present information that is new to their peers.

11. When reporting this out, the teacher might let the students know that the teacher will be calling on students rather than asking for volunteers and if the student is unable to provide the correct information, the teacher calls on the partner etc. until the correct information is expressed. Then those who previously answered correctly are required to repeat the correct information. This holds all students accountable.
12. The teacher asks the students, how can we prove that respiration gives off carbon dioxide and photosynthesis uses carbon dioxide in appropriate living things. (This is the bridge between the Exploratory Phase and the Discovery Phase.) The process:

Students work in cooperative groups consisting of two pairs, who have been assigned to work together for 6 weeks.
Each team has an assigned “clarifier” who is empowered to come to the teacher for clarifications.
Each team comes up with the preliminary ideas regarding activities that could be used to prove that respiration gives off carbon dioxide and photosynthesis uses carbon dioxide in living things.
The teacher “works the room” using a checklist to record participation. (See Suggestions to the Teacher for additional details regarding the checklist.)
The main purpose is to have students begin to think about the upcoming Discovery Phase performance task.

DISCOVERY PHASE
(estimated time: two 45 – minute class periods)

Performance Task (including planned interventions and audience beyond the teacher)
Students will work in teams to develop and perform an experiment to demonstrate each of the following statements:

Plants carry on photosynthesis and use carbon dioxide.
Plants carry on respiration and release carbon dioxide.

(The task will include writing an experiment report that includes labeled diagrams.)

Planned Intervention: Materials Selection

1. As a way of introducing students to the process, the teacher conducts a planned intervention, which employs a glass ball that contains water in which there is algae and fairy shrimp. The purpose of this intervention is to engage students in a discussion about living in an enclosed environment.

The process:

The class discusses how the organisms cycle CO2 and O2. What processes does each use regarding CO2 or make regarding CO2?
The equations for photosynthesis and aerobic respiration are written on the board.
The teacher or a volunteer draws arrows to show the cycle and flow of CO2.
Probing questions are used. What would happen to the shrimp if the algae die? (The shrimp would die.) What would happen to the algae if the shrimp dies? (The algae would live.)

2. Students are then given materials, or made aware of all available materials, from the materials list, and are required to select what they are going to use. Students are then required to justify why they have made their selections. (See Resources Made Available to Students)

Experimental Plan

3. Students create an experimental plan regarding the performance task. The process:

Students working in teams write up their process.
Each student signs the paper signifying that she agrees to the plan.
As the teams are developing their plans, the teacher “works the room” asking questions.
The teacher reads each plan that night and gives the teams feedback.
Failure is allowed to take place.
The real learning takes place when the experiments are discussed. (For a variety of reasons students don’t always get terrific results. Sometimes they don’t put enough bromothymol blue in the tube or they don’t put it in the correct light conditions.)

Spontaneous Interventions

4. The influence of light and shade on the experiment: as students work, the teacher sets up a growth light in the room and cleans out a cupboard. Through these activities and more expressly if necessary students are made aware of the light and dark areas that are available. This may clue the teams in to the fact that both are needed for a really good experiment.

5. While the student teams develop and carry out their experiment, the teacher works the room and spontaneously intervenes as necessary to focus the students’ attention on key considerations. This is usually done through the use of probing questions.
6. If through ”working the room”, the teacher determines that a planned intervention regarding the review of the scientific method and the need to test for one variable is called for, one should be provided. (Students need 2 control tubes of just bomothymol blue to observe color change: one tube for the blue bromothyol blue and one for the green or yellow bromothyol blue.)

Planned Intervention

7. After students have designed and set up their experiment on day two, the teacher may provide a graphic organizer comparing photosynthesis and respiration. Students could include the materials in the equation, where it occurs in the cell, the types of organisms it occurs in, and when that process occurs in a 24-hour day. This is a good summary of the information. The process:

The teacher provides the shell of a graphic organizer representing the relationship of respiration and photosynthesis and then directs the students to individually fill it in the best they can. (2 minutes)
Then using the pair/share process, they compare and synthesize their results. (3 minutes)
Pairs share their information; the teacher summarizes using an overhead transparency. The teacher leads the class to fill in the information that may have been excluded.
For an example of a shell graphic organizer refer to Midwest Publications, Critical Thinking Press & Software, Organizing Thinking –Book 2, Compare and Contrast Diagram.

Planning the Work and Working the Plan
Day Two: Students check their results and create their data table and work on their report. Each student prepares a brief written report to explain what he or she did and the results obtained. They must also include what would happen to the carbon dioxide once it is released, or how the carbon dioxide was available for their experiment. Diagrams to show what they were trying to prove the design of the beginning of the experiment, the data received at the end of the experiment, and the flow of carbon dioxide must accompany their report as visual aids.

Task Specifications for Developing the Student-Generated Product/Process
The specifications regarding the task are enumerated in the assessment rubric.

Assessment of Performance Task

Dimensions of a written report of a student-designed and conducted experiment regarding plant respiration and photosynthesis	Criteria for a score of 4	Criteria for a score of 3	Criteria for a score of 2	Criteria for a score of 1
Appropriateness of the experiment Intent Design	The intent of the experimenters’ is clearly expressed. The design of the experiment is connected to the experimenters’ intent.	The intent of the experimenters’ is imprecisely expressed. The design of the experiment seems to be connected to the experimenters’ intent	The intent of the experimenters’ is unclear. The design of the experiment is not related to the task.	The intent of the experimenters’ is unclear. The design of the experiment is not related to the task.
Experimental Steps	All the steps of the experiment are included. All the steps of the experiment are clearly described	All the steps of the experiment are included. Most of the steps of the experiment are clearly described.	A few of the steps of the experiment are not included. Some of the steps of the experiment are not clearly described.	Many of the steps of the experiment are not included. Few of the steps of the experiment are clearly described.
Data/Conclusions	The conclusions drawn from the experiment are clearly stated. The data supports the experimenters’ conclusions regarding what happened to the bromothyol blue after the carbon dioxide was released. The data supports the experimenters’ conclusions regarding how the carbon dioxide was made available for the experiment. All appropriate data was collected.	The conclusions drawn from the experiment are stated. The data tends to support the experimenters’ conclusions regarding what happened to the bromothyol blue after the carbon dioxide was released. The data tends to supports the experimenters’ conclusions regarding how the carbon dioxide was made available for the experiment. Most of the appropriate data was collected	The conclusions drawn from the experiment are not clearly stated. Most of the data supports the experimenters’ conclusions regarding what happened to the bromothyol blue after the carbon dioxide was released. Most of the data supports the experimenters’ conclusions regarding how the carbon dioxide was made available for the experiment. Some appropriate data was collected.	The conclusions drawn from the experiment are clearly stated. Little of the data supports the experimenters’ conclusions regarding what happened to the bromothyol blue after the carbon dioxide was released. Little of the data supports the experimenters’ conclusions regarding how the carbon dioxide was made available for the experiment. Little appropriate data was collected.
Diagrams	The diagrams accurately and clearly depict the experiment. The diagrams depict the experiment’s relationship to the statement being proved by the experiment.	The diagrams accurately depict the experiment. The diagrams to some degree depict the experiment’s relationship to the statement being proved by the experiment	The diagrams do not clearly or accurately depict the experiment. There is little relationship between the diagrams and the statement being proved by the experiment	The diagrams are unrelated to the experiment. There is no relationship between the diagrams and the statement being proved by the experiment
Resources to Be Made Available to Students Textbooks Test tubes with screw tops Bromothymol blue Bromothymol yellow A beaker with water with elodea and/or duckweed Tape Marking pens A second beaker to put tubes in. Graduate cylinder a light source Dark cupboard

Suggestions for the Teacher

Students sit in cooperative groups all year so time is saved in their pair and their cooperative group.
The “working the room” checklist mentioned in step 12, bullet 4, includes such categories as: assumes role in cooperative group, speculates on how to approach problem, clarifies the concepts, remains focused, dialogues about results, can order data, can explain/defend ordering of data, can connect data/variables to experiment design, switches roles in group, contributes verbally to task, contributes physically to task, encourages group members, helps with presentation.
The experiment reports can serve as the basis for class presentations. This gives the students an audience beyond the teacher and helps to reinforce the content as well as the scientific method.
Have students put their tubes on white paper to observe color changes.
The experiment reports can be used to fulfill state lab requirements.

This lesson incorporates ideas, and procedures created by Becky Buckingham.

Applying Standards Based Constructivism: A Two-Step Guide for Motivating Students Photosynthesis and Respiration

Applying Standards Based Constructivism:
A Two-Step Guide for Motivating Students
Photosynthesis and Respiration