6th Grade · Science · Activity · shared by Luke Morgan
This free 6th Grade Science activity explores plant nutrients, nitrogen fixation, and diagnosing why plants turn yellow in a detective scenario.
The Case of the Pale Pea Patches
The urban community garden at Westside Middle School is usually a sea of vibrant green. However, this week, the garden manager, Sam, noticed something troubling. The snap pea plants in Section A are turning a sickly pale yellow. The strange part? Section B, which is full of lettuce, looks perfectly healthy. Even stranger, both sections are being watered exactly the same amount using an automatic timer. Sam has ruled out dehydration, but the peas are failing to thrive. As a junior soil scientist, your mission is to investigate the evidence and solve the mystery of the yellowing peas.
Phase 1: Initial Evidence Log
Read the background information and the Garden Observation Report below. Use this data to begin your investigation.
Garden Observation Report
Crop Type: Snap Peas (a member of the legume family).
Current Condition: Leaves are light yellow; growth has slowed significantly.
Watering Schedule: 2 gallons per square foot, twice weekly (Soil is moist but not flooded).
Soil History: This plot was used for heavy-feeding corn crops for three years before the peas were planted. No new fertilizer has been added this season.
Nearby Plants: The lettuce in the neighboring plot is dark green and healthy.
Based on the report, what is the most significant clue that suggests water is not the problem? Explain your reasoning.
Phase 2: The Lab Dossier (Clue Discovery)
Sam sent a soil sample and a plant sample to the lab. Review these three "Clue Cards" to understand the biological processes at work.
Clue Card #1: Nutrient Profile
Plants require nitrogen to produce chlorophyll, the green pigment used for photosynthesis. Without enough nitrogen, leaves turn yellow. The soil in Section A is found to be "Nitrogen Depleted" due to previous years of heavy farming.