How Earth's systems work and how people change them: ecosystems and natural cycles, population and resource use, energy sources, pollution and environmental health, and climate change and sustainability.
Accuracy –Last test –
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How Recall Ladder tracks your progress
Learning: each topic teaches first, then asks with 2 choices. Every correct answer adds a choice; a miss takes one away.
Learned: you got it right with all 4 choices. It will come back on a later day for a quick review.
Mastered: you remembered it in a review on a later day, not just in the same sitting.
Long-term: you've kept remembering it in reviews spread over several weeks.
Needs review: you missed it in a review. It comes back soon with fewer choices, and needs another correct answer on a later day to be mastered again.
Reviews get further apart each time you remember, and come back sooner when you don't. Taking a test never changes your progress.
Topics you finished before reviews were added still count as learned: they just get one quick review to confirm.