High School Students' Mnemonic Devices for Mohs Hardness Scale

Journal of Geoscience Education, Jan 2006 by Harman, Pamela E, Rule, Audrey C

ABSTRACT

Eleventh and twelfth grade students in five earth science classes made charts or mineral facts, mnemonic cartoon drawings, and corresponding poetry couplets for minerals on the Mohs scale of hardness. Students' products revealed they enjoyed the activity and learned many mineral concepts. The activity gave the instructor the opportunity to identify and correct several student misunderstandings. Many students displayed creativity in organizing their poems and drawings by a theme, using hardness numbers to represent two things in depictions, using homonyms, and incorporating humor in the cartoons. A rubric for evaluating student work addressed six aspects: correct mineral facts, mechanics of work, poem message, rhythm/rhyme, images, and creativity.

INTRODUCTION

This project describes the work of five classes of eleventh and twelfth grade earth science students who practiced the Mohs scale of hardness by creating mnemonic drawings with poetry couplets for each mineral of the scale as suggested in "The Rhyming Peg Mnemonic Device Applied to Learning the Mohs Scale of Hardness" (Rule, 2003). In this article we will first describe why this method is effective, explain the students' assignment and provide a scoring rubric, then present some of their products and discuss the positive outcomes of the activity.

Enhancing Memory - Five basic conditions assist a person in committing information to memory: meaningfulness, organization, association, visualization, and attention (Higbee, 1996). The Mohs scale poetry-drawing project took these into account as described below.

The hardness scale information was made meaningful through laboratory activities during which students tested minerals for scratch hardness against each other and standard items such as a penny, steel nail, window glass, and porcelain plate. The crystal structures and bond strengths of the minerals were discussed in class and addressed in connection with configurations of silicon tetrahedra (isolated, single chains, double chains, frameworks, sheets) related to Bowen's reaction series.

The Mohs scale is organized from tightly bonded structures with smaller, more highly charged cations and covalent bonding (like diamond and corundum) to silicate minerals with framework structures (topaz, quartz, feldspar) to structures with more ionic bonding with larger anions or anion groups (apatite, fluorite, calcite, gypsum) to layered structures with weak van der Waals bonds (talc). Students looked at the molecular models of graphite and diamond and discussed the structure and bonding of each mineral. Students continued this organization scheme of weaker to stronger structures by writing their poems of the minerals in order and including some of the structural characteristics of the minerals in their projects.

Students connected previous knowledge with the new Mohs scale information by making drawings that associated each mineral with something else they knew. Students used the rhyming peg mnemonic device, an effective system of remembering the numerical order of items through memorization of a set of common things (the "pegs") that rhyme with each number (Bellezza and Bower, 1982; Higbee, 1996), as they associated each mineral with an item that rhymed with the hardness number. They found clever ways to combine extra information about each mineral and to make personal connections.

By producing an image of the many connected facts as a cartoon drawing, students visualized each mineral with its "peg" object and number on the Mohs scale. Such visualization is more powerful than verbal learning because images are stored both pictorially and as words in the brain, increasing the connections and paths to remembering.

Finally, nothing can be learned unless one directs attention to the new information. Students focused their attention on the order and characteristics of the minerals of the Mohs scale as they searched for appropriate rhyming words and personalized the information. The creative approach of writing simple poetry and making cartoon drawings made the task interesting, keeping students' attention.

ASSIGNMENT

The teacher showed students the mnemonic drawings from Rule (2003) and discussed why they might help students remember the Mohs scale. Then the three parts of the project were introduced: 1) create a chart of the minerals of the Mohs scale with their properties, occurrences, and uses; 2) write a poem containing a rhyming couplet for each mineral that associates the mineral with its hardness number and a rhyming object; 3) make a cartoon representation of each mineral related to the poem. Each drawing needed to display the information contained in the poem along with two other mineral facts. To help students fulfill all the project requirements, the instructor gave them a scoring rubric at the beginning of the assignment. After the assignments were graded, some improvements were made to the rubric to make it more explicit. The improved rubric is shown in Table 1. Students worked individually and were given two weeks to complete the assignment.