IB ESS 5.1-HL-L2 Why do soils develop differently? Lesson Walkthrough

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

Four sites in one fictional catchment have very different soils. Students build and challenge explanations using climate, organisms, relief, parent material and time, then test whether a comparison genuinely isolates the factor it claims to test. The activity turns a list of soil-forming factors into a connected causal model. The lesson broadens from a hillslope to tropical, temperate and polar settings, and to calcareous and volcanic parent materials. Students finish by designing the most informative next comparison, recognizing that a plausible mechanism is not the same as proof from an observational table.

Teacher response guidance is included in the walkthrough, not in a separate answer-key file.

Included: editable teacher walkthrough in Word and matching 13-page PDF; editable student reproducibles in Word and matching 4-page PDF. Classroom visual files are included.

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