IB ESS 2.5-L3 Does an older ecosystem work differently? Lesson Walkthrough

This 60-minute IB ESS lesson is for SL and HL students on the first-assessment-2026 course.

Succession changes more than the height of the vegetation. Students separate biomass from production, interpret a multi-variable time series and trace changes in soil and nutrient cycling. A disturbance test then distinguishes resistance from recovery, showing why biodiversity can support stability without guaranteeing that the oldest or most species-rich system wins every comparison.

The teacher walkthrough includes preparation, a five-phase sequence, prompts, response guidance and an optional extension. Teacher-only response guidance is separate from the student reproducibles; no separate answer-key file is supplied.

Included: editable teacher walkthrough in Word and matching 17-page PDF; editable student reproducibles in Word and matching 7-page PDF. Classroom visual files are included.

The student resources also appear in the teacher PDF appendix. Fictional cases and model data are identified where used; supplied datasets and simulations are not completed fieldwork. Follow the walkthrough’s preparation and safeguards for practical or digital options.

Independently authored by The Science Shop; customer-file integrity and packaging audited. Single-teacher classroom licence.