Matter is an essential science topic that is often challenging to teach at the early elementary levels. Learning about matter helps students develop a solid foundation for more complex concepts that are taught in later years. Make this abstract concept developmentally appropriate for children by engaging them in investigations that focus on concrete or observable aspects of matter and its interactions. This month's activities allow students to develop an "understanding of observable properties of materials [which] is developed by … analysis and classification" (NGSS Lead States 2013, p. 15). This months trade books are: (1) "Rubber vs. Glass" (Lawrence F. Lowery); and (2) "What's the Matter in Mr. Whiskers' Room?" (Michael Elsohn Ross). In the first activity students test a variety of different materials to determine which is best suited for certain tasks. In the second activity students make observations of different powders to determine their physical properties and their interactions with different liquids, and to identify an unknown sample through testing and using previously recorded information.