Forest and meadow ecosystems, and recognizing edible vs. poisonous plants.

Nature zones (Tundra, Taiga, Steppe) and major Russian rivers.

It was a quiet Tuesday morning when Timofey sat down for his 4th-grade "The World Around Us" final test. He looked at the first page and sighed. Suddenly, the ink on the paper began to swirl, and the classroom faded away. Timofey wasn't at his desk anymore—he was standing in the middle of a vast, icy plain.