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The Arizona STEM �Acceleration Project

2025

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Cultivating Futuress

Where learning takes root and futures grow: This is the first lesson that was used for a project that took learning beyond the classroom and into the garden, where students gain hands-on skills, explore career pathways, and grow alongside their peers. Its impact extends beyond graduation, continuing to benefit both students and the community.

This lesson specifically focused on one of the early lessons in preparation of planting: Leaf Disc Assay/Observe Bubbles-Leaf in Water.

9th-12th Grade

Lohr

The Arizona STEM Acceleration Project

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Notes for teachers

List of Materials

This lesson maybe taught to a Life Science or Biology inclusive general education classroom at the high school level.

This lesson takes place in one 45-50 minute class period.

Students will be placed in small groups.

An emphasis on teaching mixed group students with scaffolding and supports built in to meet students where they are at academically.

Multiple modalities, UDL, and STEM practices utilized.

Materials

Elodea or spinach leaf disks
Hole Punch
Syringe
Baking Soda
Diluted liquid dish soap
Beakers/cups
Water
Light source
Timer
Exit ticket slip

and/or Adaptations/UDL:

Fresh green leaves from a plant
Beakers
water
Funnel
Test tube

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AZ Standards

Life Science – L2: Organisms require a supply of energy and materials for which they often depend on, or compete with, other organisms.

Essential HS.L2U1.19 Develop and use models that show how changes in the transfer of matter and energy within an ecosystem and interactions between species may affect organisms and their environment.

Plus HS+B.L2U1.3 Use mathematics and computational thinking to support claims for the cycling of matter and flow of energy through trophic levels in an ecosystem.

Science and Engineering Practices

plan and carry out investigations
analyze and interpret data
use mathematical and computational thinking
construct explanations and design solutions
obtain, evaluate and communicate information

Next Generation Science Standards (NGSS)

High School (HS)

HS-LS2-3: Construct and revise an explanation based on evidence for the cycling of matter and flow of energy in aerobic and anaerobic conditions. This focuses on how organisms use and transfer energy under different conditions.�
HS-LS2-5: Develop a model to illustrate the role of photosynthesis and cellular respiration in the cycling of carbon among the biosphere, atmosphere, hydrosphere, and geosphere.

ACT Alignment Standards

Interpretation of Data:

IOD 201: Select one piece of data from a simple data display (like a food web diagram)�
IOD 301 / IOD 302: Work with more complex data, understand terminology, and interpret patterns

�

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Objectives:

By the end of the lesson, students will be able to:

Write and explain the balanced equation for photosynthesis.�
Describe how light, water, and carbon dioxide are used to produce glucose and oxygen.�
Analyze how different photosynthetic adaptations (C3, C4, CAM) provide survival advantages in different environments.

These same goals written in foundational language:

By the end of the lesson, students will be able to:

Explain that plants need sunlight, water, and carbon dioxide to make their own food.�
Describe that this process is called photosynthesis and produces sugar (glucose) for energy and oxygen as a waste product.�
Recognize that different plants have different ways of doing photosynthesis, which helps them survive in their environments.

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Agenda

55 minutes

1. Warm-Up / Engagement (5 min) Students respond to a question

2. Direct Instruction – Big Idea (10 min) Teacher explains the photosynthesis equation and breaks down each part (reactants → products).

3. Activity (20 min) - Leaf Disc Assay/Observe Bubbles-Leaf in Water

4. Making Connections (10 min) Matching Game

4. Wrap Up/ Exit Ticket (5 min) - Quick Discussion/Complete the exit ticket

See the notes section for this same agenda adapted for UDL.�

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Intro/Driving Question/Opening

Warm-Up / Engagement (5 min)

Ask: “If plants don’t eat food, how do they get energy?”

Allow students to discuss it amongst themselves and share out after. Show time-lapse of plant growth.

https://www.youtube.com/watch?v=ECibetK2EYI

OR

Adaptation/UDL:

Compare a healthy vs wilted plant - bringing in the physical plants would be best.

Ask: “Why does one look stronger?”

Allow students to discuss it amongst themselves and share out after. Show time-lapse of plant growth. (Use the link above.)

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Photosynthesis and Plant Growth Lesson

Direct Instruction – Big Idea (10 min)

Explain photosynthesis equation and break down each part (reactants → products).

OR

Adaptation/UDL:

�Use visuals/icons (sun 🌞, water 💧, air 🌬️, plant 🌱, sugar 🍬, oxygen 🌬️) to show what plants need and make.

Balanced chemical equation:

6 CO₂ + 6 H₂O + light → C₆H₁₂O₆ + 6 O₂; chloroplast structure

______

Formula in Pictures/Words:� 🌬️ Air (carbon dioxide) + 💧 Water + 🌞 Sunlight → 🍬 Sugar (plant food) + 🌬️ Oxygen (for us)

Writing Notes For Better Recall

Have the students copy the chemical equation onto either a piece of paper or whiteboard.(You could make a worksheet for them.) Breakdown the chemical equation for them using words. If you have them draw pictures under the words, it will help them to recall the formula.

Formula:� 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂

In Words:

6 carbon dioxide molecules (from the air)�
combine with 6 water molecules (from the soil)�
using light energy (from the sun)�
to make 1 glucose molecule (sugar for energy)�
and 6 oxygen molecules (released into the air).�

Summary: Plants use air, water, and sunlight to make sugar for food and oxygen for us to breathe.

OR

Adaptation/UDL:

Formula in Pictures/Words:� 🌬️ Air (carbon dioxide) + 💧 Water + 🌞 Sunlight → 🍬 Sugar (plant food) + 🌬️ Oxygen (for us)

In Words:

Plants take in air (carbon dioxide).�
Plants drink water through their roots.�
Plants use sunlight for energy.�
This makes sugar (their food) and oxygen (they give it to us).�

Summary: Plants eat sunlight, water, and air to make food and oxygen.

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Photosynthesis and Plant Growth Lesson

Activity: Seeing it in action

Leaf disk assay experiment

See directions in the notes
You will need to make a data collection sheet for your students. I had my students make their own. By doing so, I was able to observe their knowledge as well as reinforce the importance of understanding how to read a table and record data.

Background Information

This experiment measures the rate of photosynthesis by observing how quickly leaf disks, infiltrated with a baking soda (sodium bicarbonate) solution, float to the surface of water when exposed to light. Oxygen produced during photosynthesis fills the air spaces in the leaf disks, making them buoyant and causing them to rise, while cellular respiration consumes oxygen, but the net result is still oxygen production. The time it takes for the disks to float can be recorded to calculate the rate of photosynthesis under different conditions.

Note:

Students should already be familiar with the following vocabulary terms: photosynthesis, glucose, chloroplast, stroma, thylakoid, and C3/C4/CAM pathways.

Hands-On Activity:

If you haven’t conducted this experiment before, I recommend trying it yourself once or twice to build confidence before guiding your students. When introducing it to the class, consider dividing students into small groups. This approach encourages the sharing of materials, fosters teamwork, and helps students gain confidence by discussing the process with their peers.

Materials You’ll Need:

Fresh plant leaves
Hole punch
Syringe
Baking soda (sodium bicarbonate)
Diluted liquid dish soap (surfactant)
Water
Clear cups or beakers
Light source (e.g., desk lamp)
Timer

Procedure:

1. Prepare the Solution:�Dissolve 1/8 teaspoon of baking soda in 1 ¼ cups of water to create a 0.2% sodium bicarbonate solution. Add one drop of dish soap to this solution to act as a surfactant.

2. Create Leaf Disks:�Use a hole punch to cut uniform disks from the fresh leaves, avoiding large veins.

3. Infiltrate the Disks:�Place the leaf disks into a syringe and draw in some of the bicarbonate solution. Point the syringe upward, tap it to suspend the disks, and then cover the tip while pulling back on the plunger to create a vacuum. This removes air from the leaf disks, causing them to become denser and sink to the bottom of the syringe.

4. Start the Assay:�Pour the sunken leaf disks and the surrounding solution into a clear cup. Add more solution to a depth of about 2-3 inches.

5. Initiate Photosynthesis:�Place the cup under a light source and start the timer.

6. Record Observations:�Note the time it takes for each leaf disk to become buoyant and float to the top of the solution. You can do this by recording the number of floating disks at one-minute intervals.

How It Works:

Infiltration (Sinking):�The vacuum process removes air from the air spaces within the leaves, replacing them with water, which increases the disks' density and makes them sink.

Photosynthesis (Floating):�When the disks are under light, photosynthesis begins. The chloroplasts in the cells produce oxygen, which accumulates in the air spaces within the leaf disks. This added oxygen makes the disks more buoyant, causing them to rise.

Respiration:�At the same time, cellular respiration in the leaf disks consumes oxygen. The time it takes for the disks to float is therefore an indirect measurement of the net rate of photosynthesis.

Still not comfortable? Here is a video you can watch to see how it works and offers pretty good information:

https://www.youtube.com/watch?v=kYb8UE6Wx1s&t=83s

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Photosynthesis and Plant Growth Lesson

OR

Adaptation/UDL:

Observe bubbles in a leaf-in-water; Seeing it in action

This lesson will be more time intense. I suggest you begin the activity in the morning before students arrive. See notes below.
Students will actually see oxygen gas, which the leaf releases as a byproduct of photosynthesis

Note:

Students should already be familiar with the following vocabulary terms: sunlight, water (H2O), air (CO2), food (sugar - glucose), Oxygen (O), and leaf

Hands-On Activity:

I encourage you to conduct this experiment yourself if you haven’t already. Doing so will give you the opportunity to make any adjustments needed to better suit both your teaching style and your students’ needs.

Materials:

fresh green leaves from a plant (The number of leaves is dependent upon the number of small groups you form. You will need to double that number.)
beakers
water
small rocks/weights

Procedure:

Collect a leaf: Find fresh, green leaves from a living plant. Leaves from the ground or old, dry leaves won't work for this experiment.
Fill the bowl: Pour lukewarm or room-temperature water into a beaker.
Submerge the leaf: Place the leaf in the beaker. Push it down gently with the funnel. Place the test tube over the funnel.
Find a sunny spot: Move the beaker to a sunny location, such as a windowsill.
Wait: Leave the beaker undisturbed for a few hours. (*Hence, the suggestion to do this upon your arrival.)
Demonstrate and Substitute: I would suggest you demonstrate the above steps to your students or even allow them to do the steps in small groups. Than I would substitute the beakers I had prepared upon my arrival for their beakers so they get the full experience.
Observe: After the beaker has set for a while, you can see the bubbles of oxygen.

How it works:

The bubbles you see are oxygen gas, which the leaf releases as a byproduct of photosynthesis.

Plants need sunlight to perform photosynthesis, a process that converts light energy into chemical energy and produces oxygen.

In the dark, a leaf cannot perform photosynthesis and therefore does not produce as many oxygen bubbles.

Still not comfortable? Here is a short video that shows just how simple this experiment is to conduct.

https://www.youtube.com/shorts/ymli-NvWe6E

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Photosynthesis and Plant Growth Lesson

Integrating Ideas:

Play a quick matching game with students to check for understanding between today’s lesson and previous content.

Hands-On Activity:

Say: “Different plants survive in different climates because of the way they perform photosynthesis. Let’s match plants with their strategies.”�
Quick Match�

Hold up (or display) the 3 plant cards. (You can print these from the photos in the slide show.)�
Ask students to decide: Which plant stores water? Which grows with faster photosynthesis? Which uses normal photosynthesis?�
Reveal and connect terms:�

Cactus → Stores water → CAM pathway�
Corn → Fast photosynthesis → C4 pathway�
Leafy plants → Normal photosynthesis → C3 pathway�

Evolution Connection�

Ask: “Why do you think these plants developed different strategies?”�
Guide:�

Cactus/ CAM → survives in dry, hot climates by storing water and opening stomata at night.�
Corn/ C4 → grows fast in hot, sunny environments by reducing photorespiration.�
Leafy plants/ C3 → thrive in cooler, wetter climates with “normal” photosynthesis.�

4. Say: “This shows how evolution connects plants to their environments—different pathways help them survive and reproduce in the climates where they live.”�

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Photosynthesis and Plant Growth Lesson

Click here for the Exit Ticket

Let’s see what we learned today.

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Photosynthesis and Plant Growth Lesson

Planting Partnerships:

STEM Student-Led Gardens Project

Our STEM initiative establishes multiple student-led gardens across campus, including a vertical garden, vegetable garden, indoor hanging garden, and native plant courtyards. These projects transform underutilized spaces into productive learning environments that integrate science, CTE, and early childhood education.

Students design, build, and sustain the gardens, developing skills in sustainable agriculture, nutrition, and environmental stewardship. Collaboration among classes and community partners has strengthened the project, with each group contributing specialized expertise.

Looking forward, the gardens will serve as long-term resources that support STEM education, community wellness, and food security. They will provide fresh produce for those in need while equipping students with technical and agricultural skills transferable to future careers.

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Assessment

Pre-assess prior to the lesson day: Use the same questions as the exit ticket

Informal assessment: Observing throughout the lesson, experiment observation/data table

Post assessment: Exit Ticket

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Differentiation

Know the difference:

Extension/Enrichment

UDL (used throughout this lesson) is a proactive framework designed to make the learning environment accessible for all students. (See examples listed below)

Differentiation is teacher-directed strategy that adjusts instruction for individual students after the lesson begins.

For Foundational Learners:

Start lessons with simplified lessons and gradually incorporate scientific terms
Provide sentence starters or fill in the blank versions with a word bank

For Advanced Learners:

Analyze the difference between C3, C4, and CAM pathways
Explore climate adaptations & evolutionary advantages
Write explanation/design models showing photosynthesis in varying plants.

UDL Strategies:

Multiple means of representation: students can see the equation visually, read it, or listen to it verbally explained. Use of diagrams, animations, or physical models that show process. Compare adaptations using charts, images, and climate examples.

Multiple means of action/expression: students can write, type, or even model the equation with cards or manipulatives.

Multiple means of engagement: connect the concept of real-life examples, like the a leaf or garden observation.

Differentiation (remediation and enrichment): This slide should be hidden or not shared with students. This is an opportunity to make suggestions on how to modify the lesson/assessments to reach a wide range of students.

Simplified language: replace technical terms with everyday language (i.e. make their own food instead of photosynthesis)

Chunked information: break goals into smaller steps

Visual supports: use of icons for glucose, oxygen, water, and sunlight

UDL ensures multiple ways to present content, engage students, and allow them to express understanding.

Differentiation adjusts language, scaffolds, and supports students based upon their ability making the lesson accessible while maintaining the same learning goals.

Another way to think of it: UDL is a buffet that allows everyone choices, while differentiation is like an individual meal tailored by teachers for each guest after they’ve arrived.

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References:

ACT College and Career Readiness Standards

https://www.act.org/content/act/en/college-and-career-readiness/standards.html

Arizona Department of Education

https://www.azed.gov/

Carolina Knowledge Center

https://knowledge.carolina.com/discipline/earth-environmental/photosynthesis-and-floating-leaf-disks/

Centre for Universal Design Australia

https://universaldesignaustralia.net.au/differentiated-instruction-and-udl-whats-the-difference/#:~:text=The%20illustration%20is%20that%20making,explains%20the%20dinner%20party%20analogy.&text=Your%20browser%20can't%20play%20this%20video.&text=An%20error%20occurred.,useful%20and%20have%20a%20place.

ChatGPT

https://chatgpt.com/

Cool Science

https://www.coolscience.org/cool-life-science/leaf-bubbles�

Next Generation Science Standards

https://www.nextgenscience.org/

Youtube