Lesson 1 – A Breath of Oxygen
Lesson Description: In the activities and lab experiences within Lesson 1, students discover where oxygen comes from and how it can be measured. Students will review and/or explore the highlights of Earth’s link to microbes, which have historically brought about significant change. Students will measure and/or calculate the amount of O2 in the air. This introductory lesson provides background to build the importance of phytoplankton in Earth systems, and fosters many new questions that will be explored throughout the module.
Background prerequisite: Prior to this lesson, students should have minor (4th-5th grade level) exposure to photosynthesis/respiration/energy, chemical reactions, conservation of matter and graphical data analysis.
See the NGSS listed as buttons in the left-hand menu and in the chart below. The buttons on the left are grouped to show the integrated three-dimensional nature of our lessons and modules. When applicable, if NGSS are addressed outside of bundles, they are listed separately. Connections to 21st Century Learning Skills and other published standards are also included in the chart below. In addition, for this lesson, here is a breakdown of:
What Students Learn
- Throughout Earth’s history levels of oceanic and atmospheric O2 varied dramatically.
- Current O2 levels can be measured directly in air.
- To measure the O2 produced in a non-living system and apply to a living system.
- O2 in the air is produced by phytoplankton and land plants.
- Living organisms produce O2 within a single drop of water.
- A big picture view is necessary when studying real-world complexity, as is the ability to analyze subnetworks within a system.
What Students Do
- Develop and apply the skills of collaboration.
- Interpret and analyze the data from the geological history of O2.
- Observe and collect data from a lab activity and demonstration.
- Calculate and graph results from a lab activity or demonstration.
- Watch a short video to learn about plankton as a source of O2.
|Aligned Next Generation Science Standards|
|By completing this Lesson, students will work towards meeting the following Performance Expectation(s). They will also be able to use and/or develop their understanding of the listed Science and Engineering practice(s), Disciplinary Core Idea(s) and Crosscutting Concept(s).
Performance expectation(s): HS-ESS2-2 Analyzing Geoscience data to make the claim that one change to Earth’s surface can create feedbacks that cause changes to other Earth systems. HS-LS2-1 Use mathematical and computational representation to support explanations of factors that affect the carrying capacity of ecosystems at different scales; HS-LS2-5 Develop a model to illustrate the role of photosynthesis and cellular respiration in the cycling of matter among the biosphere, atmosphere, hydrosphere, and geosphere; HS-PS1-2 Construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms and knowledge of patterns of chemical properties.
Common Core: M3
CTE – #’s 4, 12
21st Century Skills – #’s 1, 2, grade level dependent
*ETS2.B Influence of Engineering, Technology, and Science on Society and the Natural World) and SEP-7: Engaging in Argument from evidence (worksheet questions explore these arguments).
“Where do living systems acquire their breathable O2?” Throughout Earth’s history, levels of oceanic and atmospheric oxygen (O2) varied dramatically and brought about major shifts in the course of Earth’s history. In a single drop of water, microbes are producing oxygen and energy for the Earth system. Students will first review the highlights of Earth’s link to microbes, which brought about significant change. Then, they will measure the amount of O2 in the air. If you are following the PBL thread, this introductory lesson provides background to build the importance of phytoplankton in Earth systems and may foster many new questions. In Lesson 2, students will learn about the production and use of O2 through photosynthesis and cellular respiration in living things across the nano- and macroscale. Later in the module, they will explore how O2 production from living things can be measured on a global scale.
Overview Table of Lesson 1:
|Lesson subsection||What students learn*||What students do*|
|See Two Options for compressing this lesson into 2 x 50 minute classes.|
|Pre-Assessment – If not using PBL, use 1 of these 2 options
||– What do I Know/ Need to Know?||– formative assessment of questions about the geological history of oxygen and the oxygen in living things.
– develop and apply the skills of collaboration.
|Part 1: Introductory Activity (~5-10 min) “Take a Breath” – From where does our breathable oxygen come?
Part 2 Chemical Change Introduction (~20 min): Demo: Rusty evidence of oxygen on earth.
Part 2 Activity (20 min): HHMI “Geological History of Oxygen”_web link 1 with Worksheet 1
Show: HHMI “The Deep History of a Living Planet”_ web link 2
|– throughout Earth’s history levels of oceanic and atmospheric O2 varied dramatically.
– when studying real-world complexity, a big picture view is necessary as is the ability to analyze subnetworks within a system.
|– Teacher-led instruction and notes – interpret and analyze the data from the geological history of oxygen.
– develop and apply the skills of collaboration.
|Part 3: Measuring Percent of Oxygen—uses Worksheet 2
– Part 3 Lab – As a Teacher Demo (15-20 min)
– Part 3 Lab – As a Demo 1st then as a student lab (optional, +10-15 min) End Part 3: Show Scripps O2 Global Oxygen MeasurementsPart 4: Analysis of results Demo and Student Lab (+20 min)—calculate breathable oxygen content in the air.
|– current O2 levels can be measured directly in air.
– to measure the O2 produced in a non-living system and apply to a living system.
|– observe and collect data from a lab activity and demonstration.
– develop and apply the skills of collaboration.
– calculate and graph results from a collection of data from lab activity or demonstration.
|Part 5: Thanking Phytoplankton (~15 min) Show: “Five Reasons to Thank Plankton” (Web link 3) and answer questions.||– oxygen in the air is produced by phytoplankton and land plants.
– living organisms produce oxygen within a single drop of water.
|– watch a short video to answer questions about plankton as a source of oxygen.|
|Part 6: Assessment (~30-50 min) How will I know they know…
– Use Parts 1 – 4 & Worksheet 3**
– Or use PBL reflections ‘Know /Need to know’ and PBL summary table
|– What do I know now?
– [PBL option] Making connections and seeing relationships in ‘Drop of Seawater.’ What questions do I still need/want to ask?
|– Discuss/answer questions in (teams)** [**or Assign individually as 2 Homework assignments after Parts 1-2 & 3-4.]
– [PBL option] Conduct reflection and ask new questions by adding to ‘Drop of Seawater’ art project.
* The “what students learn” and “what students do” in this table provide a more specific breakdown of the main learning objectives listed above.
Before class (~2 – 3 days prior to the lesson):
- Check that all web links listed in the Resources Section below (particularly “Geological History of Oxygen” HHMI Biointeractive (web link 1)*) are accessible for your students. (*See website Homepage for a list of compatible browsers and recommended for the HHMI “Click and learn” video)
- Set up the Invisible Forest module Pre-Assessment on laptops (google form), or print.
- Print group sets of (optional) Group Reasoning Seminar to use as outlined in Pre-assessment teacher notes.
- Set up “From where does breathable oxygen come?”(Powerpoint). To help planning see Two Options for compressing the lesson into 2 x 50-minute classes.
- Gather demo and lab supplies (below), and run one demo trial prior to class.
- Print (or electronically upload) student/or group copies of the worksheets and refer to the teacher KEY as needed:
Worksheet 1 (Google Doc | Word Doc) and Worksheet 1 Teacher KEY (Google Doc | Word Doc).
Worksheet 2 (Google Doc | Word Doc) and Worksheet 2 Teacher KEY (Google Doc | Word Doc)
Worksheet 3 (Google Doc | Word Doc) and Worksheet 3 Teacher KEY (Google Doc | Word Doc)
|Part 3 Lab – Supplies for Demo||Part 3 Lab – Supplies for a Class of 32 students estimated to include one demo, mistakes & make-ups):|
|1 fluff of steel wool (#00 or 0000) ~ 0.50 g||25 g steel wool (grade #00 or #0000)|
|2.5 cm diameter test tube||16 x ~2.5 cm diameter test tubes|
|100.0 mL white, distilled vinegar||2 L white, distilled vinegar|
|25 mL (or 100 mL) graduated cylinder||16 x 25 mL (or 100 mL) graduated cylinders|
|centi-(or deci-) gram balance||5 x 7 centi- or deci- gram balances|
|250 mL beaker or wide-mouth cup||16 x 250 mL beakers (or wide mouth cups)|
|metric ruler||16 metric rulers|
|ring stand / clamp (test tube)||16 ring stands / 16 test tube clamps|
|rubber band||20 thicker, flexible rubber bands|
Pre-assessment [if not using PBL option]: Invisible Forest module Pre-Assessment (10 minutes – True/False). Add the optional Group Reasoning Seminar Worksheet which is explained in the Pre-assessment Teacher Notes and Instructions. (+15 min)
Part 1: Introductory Activity (~5–10 min.)
Teacher leads the whole class discussion. Begin the discussion using the following:
- Take a deep breath and hold it as long as possible (~ 30 seconds).
- What is essential to our lives and most living systems?
- Where does the oxygen that we breathe come from?
- Is there O2 in one drop of seawater? Why or why not?
Teacher Notes Part 1: Students know the process of photosynthesis produces oxygen. Plants provide some of the oxygen on earth, but much of the oxygen plants give off is then recycled during the night to provide energy for the plants? Later in this lesson students learn more about phytoplankton, which produce 50% of the oxygen on Earth, much of it makes its way to the atmosphere. But at this point in the lesson —just let them wonder).
Part 2: Chemical Change (~20 min)
Overview: Teacher leads a whole class demonstration with iron and uses a short PowerPoint to give perspective. Then students complete a “Geological History of Oxygen” by HHMI Biointeractive (weblink 1). This “Click and Learn” activity should be completed with pre-selected teams.* (Teams, individuals, or the whole class, explore and discuss findings in this activity).
- *Plan teams: minimum of 2 teams per eons for discussion purposes.
(Example: Team #1,2 = Archeon, Team #3,4 = Proterozoic, Team #5,6 = Phanerozoic)
- Keep in mind that you will address the following during this activity:
- Graph represents estimates of O2 levels based on a variety of indirect measurements, since ancient O2 levels can’t be measured directly.
- Oxygenation of the atmosphere is an active area of research.
- General conclusions presented in this “Click and Learn” are sound and based on interpretations of currently available data, specific to this HHMI activity. The alternative site provides similar information if HHMI site is blocked.
Activity Sequence for Part 2:
- Step 1: Introduce chemical change by showing the whole class:
- 1 rusty and 1 non-rusty item (nail, junk piece, etc.). Ask students: What is making the change you observe? Where is oxygen coming from? What evidence is there of oxygen on earth?
- Step 2: Show “From where does breathable oxygen come?” PowerPoint. Use the teacher notes within the PowerPoint to guide students toward Identifying and discussing source(s) of breathable oxygen.
- Step 3. Activity: Go to “Geological History of Oxygen” HHMI Biointeractive (weblink 1) have student groups analyze and assess data from the interactive video. Use the first slide to introduce the activity. Observe the graph for all three eons.
- Hand out Worksheet 1 (Google Doc | Word Doc) (written for this HHMI video). For your reference, here is the Teacher Key (Google Doc | Word Doc).
- Groups read/interpret the graph for assigned eon*
- For more information, students use the “Howie” icons & “Get to Know the Graph”(on the HHMI homepage).
- Ask groups studying the same eon to discuss the similarities & differences they find. Then have eon groups report group interpretations to the class as a whole.
- Step 4. Summarize. Go to “The Deep History of a Living Planet” HHMI Biointeractive (web link 2) – Lecture Points 24 – 26, (show minutes 40:49 to 46:25); or use alternative National Institute of Health website
Part 3: Measuring Percent of Oxygen (~15–30 min.)
Whole-class demo, and [optional] teams lab to introduce students to how oxygen is measured in a lab using the chemical reaction of iron and vinegar. Demonstrates how the percent oxygen in air by volume can be calculated by measuring the quantity of air in a cylinder before and after iron rusts (oxidizing). [Later in the module students will observe how oxygen production from living things can be measured].
- Gather Demo and Lab supplies.
- Refer to Procedure on the Student Percent Oxygen Lab Worksheet. (Google Doc | Word Doc)
- Run one trial prior to class.
Part 3 Lab (Demo only or extend into a student lab conducted in teams
Teacher performs Lab as a Demo
Step 1: Measure/record initial mass of steel wool.
Step 2: Collect data from the Demo.
Step 3: Measure/record final mass of steel wool after allowing it to dry.
(As a replacement, you could also show this video (YouTube link – begin at 2:40 if you do not want the pre-information.)
Student teams perform Lab (see table for additional supplies (above))
Step 1: Measure/record initial mass of steel wool.
Step 2: Collect data from the Demo first.
Step 3: Use Procedure on the Student Percent Oxygen Lab Worksheet (Google Doc | Word Doc) to conduct the lab.
Step 4: Record data in the Student Percent Oxygen Lab Worksheet (Google Doc | Word Doc)
Step 5: Measure/record final mass of steel wool after allowing it to dry.
Step 6: Complete the calculations in Student Worksheet (Google Doc | Word Doc) and record group results in class spreadsheet.
Teacher Notes Part 3: At the end of Part 3, show Scripps O2 Global Oxygen Measurements The Scripps O2 Program measures changes in atmospheric oxygen levels from air samples collected at stations around the world. This sampling network provides a global and hemispheric perspective on oxygen variability. (Source:Scripps)
Part 4: Analysis of results—breathable oxygen content in the air (10 min).
Students analyze data from Demo 3A and Lab 3B (if done) using class spreadsheet.
Step 1: Discuss sources of error.
Step 2: Evaluate ‘Know and Need to know’ questions (use PBL reflections table).
Teacher Notes Part 4: Worksheet 2 Key (Google Doc | Word Doc)
- Instruct students: think about oxygen production in non-living systems (just conducted in the Lab). Compare this to how we measure oxygen production in living systems (terrestrial & ocean producers). Conduct small group discussions leading to a full class summary. Let students know they will learn more about this during the rest of the Invisible Forest module.
- See the Extension section below for topics for advanced classes. Recommended topics include: Ideal Gas Law, Dalton’s Law Partial Pressure, and “Determining the percentage of oxygen in the air”
Part 5: Thanking Phytoplankton (~15 -20 min) In this final activity students connect oxygen production to living systems. In the above lesson, oxygen content was measured in non-living chemical reactions. Now they will be asked: “What do you know about how oxygen is produced and measured in living systems? What else needs measuring about these organisms and their ecosystems? Why?* [*Later in Part 6 Worksheet 3 (Google Doc | Word Doc), students will record responses, along with answering other questions]
- Step 1: Watch the video: “Five Reasons to Thank Plankton” (web link #3)
- Step 2: Record answers to these questions in lab journals during the video.
- Step 3: Discuss answers to these questions following the video:
- What claims were made in this video?
- What evidence and reasoning are required to support or reject these claims?
- Does one drop of seawater contain oxygen?
- Does one drop of seawater contain living systems producing oxygen?
- How does this add to what you know/don’t know considering oxygen on Earth?
Part 6: Assessment (~ 30-50 min) (Assign students to same teams as in Part 2, or assign individually as two homeworks following Part 1-2 and 3-4. For [PBL option] students conduct PBL reflections‘ Know and Need to know.’ Then add components to the ‘Drop of Seawater’ project. Use the PBL summary table to formulate ideas before adding to ‘Drop of Seawater’.
How will I know they know…With reference to Parts 1 – 5 (above), use Worksheet 3 (Google Doc | Word Doc), to discuss/answer these questions in teams:
Refer to Parts 1 and 2 for questions 1-8:
- List ways in which O2 is used.
- From where does the breathable O2 come?
- Why are phytoplankton called the Invisible Forest?
- How does the Invisible Forest make life on Earth possible?
- What evidence suggests an increase in O2 in the air 700 million years ago?
- Is the O2 content in the atmosphere the same everywhere?
- Does O2 content in the atmosphere change with location, time of day, altitude?
- Is the amount of O2 in the air constant?
- How does the amount of O2 we measured compare to other times on Earth
Refer to Parts 3 and 4 for questions 9-12:
- How is O2 in an air sample measured?
- What are some errors associated with measuring levels of O2?
- Why should we “Thank Phytoplankton”?
- In the above lesson, O2 content was measured. What else needs measuring about these organisms and their ecosystems? Why?
Teacher Notes Part 6: Using Worksheet 3 Key (Google Doc | Word Doc) collect and/or observe and/or evaluate:
- Responses to questions in Worksheet 3
- Discuss team interpretations with the whole class.
- [PBL option]: review student additions to their ‘Drop of Seawater’
- Invisible Forest module Pre-Assessment
- Group Reasoning Seminar (optional) and Pre-assessment teacher notes.
- Pre-assessment key (Google Doc | Word Doc) (do not show to students)
- Worksheet 1 (Google Doc | Word Doc)
- Worksheet 1 Teacher Key (Google Doc | Word Doc)
- Worksheet 2 (Google Doc | Word Doc)
- Worksheet 2 Teacher Key (Google Doc | Word Doc)
- Worksheet 3 (Google Doc | Word Doc)
- Worksheet 3 Teacher Key (Google Doc | Word Doc)
- “From where does breathable oxygen come?”_PowerPoint (Google Slides | PowerPoint)
- “Geological History of Oxygen” HHMI Biointeractive_web link 1
- “The Deep History of a Living Planet” HHMI Biointeractive _web link 2 or National Institute of Health website
- Scripps O2 Global Oxygen Measurements (http://scrippso2.ucsd.edu/)
- “Five Reasons to Thank Plankton”_web link 3
- PBL reflections
1. Study the stoichiometry of the iron and oxygen reaction:
4 Fe(s) + 3 O2(g) → 2 Fe2O3(s).
- What substance is the limiting reactant?
- Provide supporting work & consider significant figures for the answer.
- What happens when the amount of steel wool changes? Why?
2. In an equilibrium system (assuming all available oxygen is used up in reaction), consider there is also oxygen in equilibrium with dissolved oxygen within the water.
- How much error does this assumption contribute?
- Is this error systematic or random? Why?
3. Extension topics or activities for advanced classes.
- Ideal Gas Law
- Dalton’s Law Partial Pressure
- General Chemistry Laboratory: Determination of the Percentage Oxygen in Air
Also, please see the Contributors Page (also listed in the left-hand menu) for a list of all of the teachers, scientists and students who have contributed to this module.