Part 1: Photosynthesizer or Not? Card Sort (40 min)
Introduction: If students already have a working knowledge of photosynthesis, move directly to the Photosynthesizer or Not? Cards (Google Doc | Word Doc) sort activity. In groups of 2-4 students sort 26 cards to explore the characteristics of photosynthesizers. The activity both reviews photosynthesis and reveals that not all photosynthesizers are green and plant like. And, in fact, some are so small they are invisible. The Card sort activity includes the microorganisms that are used in subsequent lessons. (This also can be done as a class, using the quick Photosynthesizer or Not?ppt (Google Slides | PowerPoint). This can also be done online with students by having them drag and drop photos into categories using this Slide. They will need to work outside of the Presenter Mode function.)
Step 1: Each group of 2-4 students works together to sort the Photosynthesizer or Not? Cards into 2 sets: “photosynthesizers” and “non-photosynthesizers.” As they organize the cards, have them write their thinking in the Photosynthesis or not? Worksheet.
Step 2: After groups finish sorting, have groups share ‘who’ they put in each group. Allow students to ask questions or challenge the placement of an organism. Keep visual notes on the overhead, to track and revisit their ideas later. Make sure to have them talk about a wide variety of the cards, including the Prochlorococcus (Pro).
Step 3: Next, ask and discuss the value and challenge to sorting organisms based on physical characteristics. (For example, coloration or size of an organism may make it difficult to decide if it is a photosynthesizer or not. Classifying based on physical or external characteristics ignores everything going on internally. To classify organisms based on a functional trait, an understanding of metabolism and/or DNA comes in.)
Step 4: Summarize the discussion and be sure to emphasize that chlorophyll is the common feature of all of the photosynthesizers (autotrophs) shown.
Final Step: Move on to Part 2
If students need more review use this (optional) Photosynthesis webquest review_review before or after the Photosynthesizer or Not? Card sorting activity, as a formative assessment. Use the Webquest Teacher key to review as a class, to build conceptual knowledge. For more photosynthesis review Labs see Extensions tab.*
Part 2: Microscopic Observation of Phytoplankton (30–60 min)
Purpose: Since the key idea for this unit is the Invisible Forest, and in particular Prochlorococcus (Pro) as the world’s most common form of phytoplankton; it would make sense to have students observe plankton for themselves, even though Pro is too small for student microscopes to resolve. The phytoplankton they do see will be tiny, so students can make the connection there are even smaller photosynthesizers in the water – and they make a huge contribution to global productivity.
Before class: Prepare microscopes and slides for groups of 3-4. Read part 1 of Teacher Lesson Plan / Background Phytoplankton Spectrophotometer Lab (Google Doc | Word Doc) Part 1A. *The best plankton are gathered in late summer/late spring (start of school year/end of school year) from local fresh or saltwater source or drawn from a saltwater tank cultured throughout the year.
A: Microscope observations of plankton (30–50 min)— Students prepare slides with a drop of water, (may be fresh or seawater plankton culture) observe plankton and make a sketch in lab notebook.
B: Show video Ted talk “The Secret Life of Plankton” (6 min) —This would be a great segue between plankton microscope observations and the introduction of Pro as world’s most numerous phytoplankter.
Part 3: Pro Anatomy Slide Show (30 min)
Introduction: Use this part of the lesson to explore Prochlorococcus (Pro) scale, anatomy, organelle function, and life at nano-scale. The Pro Anatomy Slideshow (Google Slide | PowerPoint) is an interactive illustration to learn about the internal workings of Prochlorococcus (phytoplankton). Use as an oral review of Pro cell functions, that shows off the unique structures of the smallest of photosynthesizers and their scale next to other plankton. The slideshow also has information about Pelagibacter a heterotroph in a somewhat symbiotic relationship with Pro.
Before Class: Download Pro Anatomy Slideshow (Google Slide | PowerPoint) (preview sequence and teacher notes); Print 1 per student on TWO pieces of Paper Pro Anatomy and scale_worksheet (Google Doc | Word Doc); Pull up on computer: video Meet the obscure microbe that influences climate, ocean ecosystems, and perhaps even evolution and link to Learn Genetics Size and Scale
Step 1: Hand out the Pro Anatomy and Scale Worksheet (Google Doc | Word Doc) (here is is in PDF for better formatting) . Use teacher notes in Pro Anatomy Slideshow (Google Slide | PowerPoint) to present the cell structures and functions to students. Help apply their knowledge of photosynthesis in eukaryotes to understanding photosynthesis in prokaryotes, specifically Prochlorococcus(Pro).
Step 2: Students annotate Pro Anatomy and Scale Worksheet (in PDF) to tracing cell parts and function. Depending on your students, you may want to hand out pages 1 and 2 together or separate. This depends on how much scaffolding your student need. In either case, prompt your students to think of light waves interacting with chlorophyll in thylakoid membranes. [CCC Systems] [CCC Energy and Matter]. Compare the size and scale of Pro and its environment with wavelength of blue light it absorbs in photosynthesis (wavelength on worksheet is to scale).[CCC Systems] [CCC Energy and Matter].
Step 2b: For more on scale go to University of Utah Learn Genetics for sliding scale with powers of 10. Use Learn Genetics Size and Scale sliding bar to show relative sizes of cells and molecules. This Scale of the Universe YouTube video also does a terrific job showing providing perspective.
Step 3: Present video short (3.5 min) Meet the obscure microbe that influences climate, ocean ecosystems, and perhaps even evolution (to play click on image at start of Science Magazine article).
Step 4: Lead students through a discussion of Prochlorococcus place in oceanic/global productivity to bring content of Pro anatomy and ideas in slideshow together.
Step 5: Record current estimates of Pro, Pelagibacter, and virus load in their ‘Drop of Seawater’ diagram to loop their learning and reenforce scale.
Final step: Understand – Describe/Explain (keep it simple)
- Ask students to do a rough sketch from memory of Pro cell, virus, and extracellular vesicle; and how cell functions. Write out general function of photosystem to add to the diagram. OR….
- [PBL option] Revise and add any new information you’ve learned during this lesson to your ‘Drop of Seawater.’ Use the PBL summary table to help formulate ideas, before adding them to the diagram.
*Additional Photosynthesis Review: (Go to Extensions tab) choose among these optional extensions to give students practice in lab skills and build stronger conceptual knowledge of the process of photosynthesis:
- Photosynthesis Extension Labs (4) —each of the four labs is adapted to focus on oxygen production. Each Lab contains materials and procedures, including technology applications with Vernier probes.
- These experiments aim to provide context for the role chlorophyll plays in capturing and transforming light into usable energy, while producing oxygen as a waste product. Develops understanding of the role photosynthetic organisms play in providing oxygen for heterotrophs.
- Photosynthesis Review_review webquest
Students may be challenged to send messages via Morse code after experimenting with Semaphore.
OpAmp Ideas,How to Build an Operational Amplifier,Additional mp3 file, Signal and Noise in the Op Amp, Sample Graphs
Building The Op Amp – advanced (PowerPoint, Student Activity)
Materials Not Included (op-amp) (for ~25 students, ~8 groups of ~3):
9V Batteries (2 per group)
Alligator Leads (4 per group)
Audio Device (iPod, Computer with audio jack, or similar)
Voltage Probes with Real-Time Data Collection capabilities (Vernier or Pasco) (2 sets per group)
Mini Breadboard (1 per group)
Jump Wires (approx 9 smaller wires per groups)
741 IC Chip (1 per group)
22 μF capacitor (1 per group)
1kΩ variable resistor (1 per group)
1kΩ resistor (1 per group)
47kΩ resistor (1 per group)
Battery caps with leads (2 per group)
Speaker (1 per group)
Audio Plug (1 per group)
Students in small groups will build an OpAmp using a 741 IC chip and a breadboard. The PowerPoint OpAmp Circuit Assembly introduces the breadboard and the common wiring located underneath (slides 1-3). The schematic for the circuit they will assemble is shown on slide 4. The final slide illustrates the assembly step by step in the same sequence as the printed student instructions Signal and Noise in the Op Amp prompt a set of actions to explore the voltage input & output signal and noise related to different elements in the op amp circuit. The final assignment is a written summary with embedded graphs of their findings. Students will need to have preloaded mp3 files 60Hz_White_Noise.mp3 and 800Hz_White_Noise.mp3 into their ipods or a computer with an audio jack. Students are given the freedom to develop a means for estimating noise in the sinusoidal signal based on their previous experiences with the directed radio example. Depending on the students’ background with superposition of waves, Vernier’s Fast Fourier Transform (under insert / additional graph) is a possible means to analyze the more complex 800 hz sample. Sample graphs for the prompts can be found here Sample Graphs for Signal and Noise Op Amp Activity. In the extension section below is a link to a number of possible investigations as well as additional mp3 files.
Science Friday article on Pro discovery – The Invisible Forest Under the Sea
Penny Chisholm’s TED talk on Prochlorococcus and discovery.