Lesson Plan

• Describe the roles of source and sink tissues in phloem transport.
• Explain the pressure‑flow hypothesis and how active loading creates a pressure gradient.
• Identify the sequential steps of phloem loading, bulk flow, and unloading.
• Illustrate the function of companion cells in assimilate movement.
• Compare typical source and sink organs in a flowering plant.

• Projector or interactive whiteboard
• Diagram of phloem loading/unloading (digital or printed)
• Worksheet with source‑sink comparison table
• Markers and chart paper for group diagram
• Sample leaf and root specimens (optional)
• Exit‑ticket cards

Begin with a quick question: “How does the sugar produced in a leaf reach a growing fruit?” Connect this to students’ prior knowledge of photosynthesis and xylem transport. Explain that by the end of the lesson they will be able to state the key movement of assimilates in the phloem and outline the underlying mechanism.

1. Do‑now (5’) – short quiz on photosynthesis terms and basic plant transport.
2. Mini‑lecture (10’) – present the key statement and pressure‑flow hypothesis using the diagram.
3. Guided analysis (10’) – students label source vs. sink in the provided table and discuss in pairs.
4. Interactive simulation (10’) – explore phloem loading/unloading online; record observations on a worksheet.
5. Group activity (10’) – construct a flow diagram on chart paper, explaining each step of the pressure‑flow process.
6. Check for understanding (5’) – exit ticket: write the concise statement about assimilate movement in one sentence.

Recap the sequence of source → loading → pressure‑driven bulk flow → unloading → sink, emphasizing the role of osmotic pressure. Collect exit tickets to gauge mastery and assign a brief homework: students sketch and label a phloem transport diagram for a different plant organ.