By Maura Bostwick Neill. Once unzipped all files are in PDF format. Sets include crosswords, matching pair puzzles, word searches and vocabulary review sheets. Topics of Energy resources, Ecosystems, Cycles in Nature, Environmental issues and the interrelatedness of living things and their environment. Worksheets are also sold separately. I use the puzzles for fun review before a quiz, and the vocabulary review sheets as study guides for a textbook chapter.