An introductory tour of the universe: the sky and the motions of the Earth, Moon and Sun, gravity, light and telescopes, the planets and small bodies of the Solar System, the Sun and the lives of stars, and galaxies and the Big Bang.
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.