The world contains a limited number of elements--the purest form of matter. But when these elements are combined, the possibilities are limitless! Water, carbon dioxide and salt are just a few examples of how elements can be combined to form entirely new substances. Many of these combinations occur naturally, while others are man-made. Students will learn the difference between compounds and mixtures, and see how scientists are able to combine the Earth's elements to our benefit. An interesting hands-on activity is included. One of the 16 volumes in the Physical Science in Action series in the Schlessinger Science Library. Part of the Schlessinger Science Library in Action Collection. This title correlates to the National Science Education Standards for Physical Science--properties and changes of properties in matter, motions and forces, and transfer of energy. This program includes a teacher's guide. (Author/MM)