CONTENT
In the state of Michigan, middle school students learn concepts including classifying substances based on their physical properties, arrangement and motion of atoms and molecules, and describing examples of physical properties (Straus, n.d. p. 78). One type of physical property is density. In order to be able to classify substances by density, students must understand the true meaning of density and how to find it.
By the end of a unit on density, students should be able to measure and define mass and volume and apply the formula for density. Students should be able to describe the physical property of a substance with given information (such as mass and volume or mass and density or volume and density) and describe the changes associated with changing one factor of density. Students should also be able to apply the concept of density to explain why an object floats or sinks in a substance.
Unfortunately, many of my students struggle with understanding this concept. The El Paso Collaborative for Academic Excellence, the Consortium for Policy Research in Education, and the Consortium for Achievement in Mathematics and Science (10, Sept) studied three classes of 7th graders to determine where they struggle with learning the concept of density. They found that students do not have a clear understanding of volume. To find the volume of an irregular object, students knew to observe the displacement of water, however, the majority of students could not explain why this displacement occurred correctly (El Paso, n.d., p. 1). Eugene Gennaro (1981) found during his study of 290 ninth grade students that students are confusing the ideas of mass and volume when performing experiments (p. 402). He found that students need a clearer understanding of the concepts of mass and volume in order to truly understand and apply density in different situations (p. 402). Finally, Victoria Deschere (2003) found that students in middle school are just beginning to think abstractly. Students continue to struggle with density because it cannot be seen with the "naked eye" and "cannot incorporate the concept into their understanding of how matter behaves" (2003). In addition, students memorize how to solve the density formula with given information, but often disassociate this with mass, volume, and explaining why objects sink and float (Deschere, 2003).
Resources:
Deschere, V. (2003, September 3). It's not waste: teaching recycling through density, phase change and solubility. Retrieved July 7, 2014, from http://teachers.yale.edu/curriculum/viewer/initiative_09.05.03_u
El Paso Collaborative for Academic Excellence, Consortium for Policy Research in Education, & Consortium for Achievement in Mathematics and Science. (10, Sept). PCK tools: density. Retrieved July 6, 2014, from http://www.epcae.org/uploads/documents/Density_pck_Sep10.pdf
Gennaro, E. D. (1981). Assessing junior high students' understanding of density and solubility. School Science and Mathematics, 81, 399-404.
Straus, K. (n.d.). Science grade level content expectations. Retrieved July 6, 2014, from http://mi.gov/documents/mde/Complete_Science_GLCE_12-12-07_218314_7.pdf?20140706174026
By the end of a unit on density, students should be able to measure and define mass and volume and apply the formula for density. Students should be able to describe the physical property of a substance with given information (such as mass and volume or mass and density or volume and density) and describe the changes associated with changing one factor of density. Students should also be able to apply the concept of density to explain why an object floats or sinks in a substance.
Unfortunately, many of my students struggle with understanding this concept. The El Paso Collaborative for Academic Excellence, the Consortium for Policy Research in Education, and the Consortium for Achievement in Mathematics and Science (10, Sept) studied three classes of 7th graders to determine where they struggle with learning the concept of density. They found that students do not have a clear understanding of volume. To find the volume of an irregular object, students knew to observe the displacement of water, however, the majority of students could not explain why this displacement occurred correctly (El Paso, n.d., p. 1). Eugene Gennaro (1981) found during his study of 290 ninth grade students that students are confusing the ideas of mass and volume when performing experiments (p. 402). He found that students need a clearer understanding of the concepts of mass and volume in order to truly understand and apply density in different situations (p. 402). Finally, Victoria Deschere (2003) found that students in middle school are just beginning to think abstractly. Students continue to struggle with density because it cannot be seen with the "naked eye" and "cannot incorporate the concept into their understanding of how matter behaves" (2003). In addition, students memorize how to solve the density formula with given information, but often disassociate this with mass, volume, and explaining why objects sink and float (Deschere, 2003).
Resources:
Deschere, V. (2003, September 3). It's not waste: teaching recycling through density, phase change and solubility. Retrieved July 7, 2014, from http://teachers.yale.edu/curriculum/viewer/initiative_09.05.03_u
El Paso Collaborative for Academic Excellence, Consortium for Policy Research in Education, & Consortium for Achievement in Mathematics and Science. (10, Sept). PCK tools: density. Retrieved July 6, 2014, from http://www.epcae.org/uploads/documents/Density_pck_Sep10.pdf
Gennaro, E. D. (1981). Assessing junior high students' understanding of density and solubility. School Science and Mathematics, 81, 399-404.
Straus, K. (n.d.). Science grade level content expectations. Retrieved July 6, 2014, from http://mi.gov/documents/mde/Complete_Science_GLCE_12-12-07_218314_7.pdf?20140706174026