64 SCIENCE SCOPE TEACHER’S TOOLKIT Linking proportionality across the science and mathematics curricula through science literacy maps by Kerri Richardson, Catherine Matthews, and Catherine Thompson Middle level science and mathematics teachers should collaborate to clarify concepts for students in each of these disciplines. The topic of proportionality is an ex- cellent choice for a collaborative effort, as understand- ing proportionality is important in both science and mathematics. The April 2003 focus issue of Mathematics Teaching in the Middle School touted proportionality as a unifying theme for the middle-grades mathematics curriculum. In Principles and Standards, the National Council of Teachers of Mathematics (2000) states: “The under- standing of proportionality should also emerge through problem solving and reasoning, and it is important in connecting mathematical topics and in connecting mathematics and other domains such as science and art” (p. 211). The Atlas of Science Literacy from AAAS offers a set of science literacy maps for grades K–12 that can serve as a useful tool in helping teachers make connections between science and mathematics. Those who teach science and mathematics could especially benefit from the Atlas. The National Science Teachers Association (NSTA) promotes the inclusion of science and mathematics in all areas of scientific inquiry. The idea of proportional reasoning is an excellent bridge into middle-grades scientific inquiry. Proportion- al reasoning is important in geometry, measurement, and probability and statistics, and science teachers de- pend on students being able to understand and manipu- late proportions. The concept of density is one way to il- lustrate proportional reasoning in science (see Activity Worksheet for a student activity on density that can be used in both science and mathematics classrooms). Sci- ence and mathematics teachers can connect the disci- plines in a way that will not only help their students but also inform their own teaching about the commonalities between mathematics and science. The National Science Digital Library (NSDL) is an online resource consisting of science literacy maps and numerous juried resources for teaching science, tech- nology, engineering, and mathematics (STEM) (see Resources). Science literacy maps are used to offer information about concepts and to help students con- struct their own understanding. They are also helpful to teachers as they provide a broad look at content and process skills across the science curriculum. Proportional reasoning and density In science instruction, proportional reasoning is impor- tant because it allows students to construct the mean- ing of scientific concepts that are being illustrated. Mathematically, density is described as a ratio of the mass per unit of volume and subsequently can be com- puted to obtain a specific value for any substance. Sci- entifically, the density of a substance can be compared proportionally between water and other substances. Water has a density of 1.0 gram of mass per 1.0 milliliter of volume. Substances that have a density greater than 1, or a mass that is larger than 1.0 gram per milliliter of volume, will sink when placed in water. Substances that have density that is less than one gram per milliliter will float. Additionally, proportional rela- tionships using the same material with different masses and their associated volumes may be graphed to show proportionality in a linear graph.