A Big 41 Puzzle Space Exploration Unit Workbook with Keys. Includes fill-in, crossword, wordsearch and matching worksheets and quizzes covering astronomy, the solar system, planets, the universe, the history of space exploration, the International Space Station, the history of NASA, the Big Bang, the origins of Earth and the moon, the future of space exploration, and the possibility of extraterrestrial life. By Derrick Neill.