Undergraduate introductory course in geoscience

Students should have learned about igneous rocks and seen the igneous rock composition chart.

We have used this activity as a homework assignment after the topic is introduced in lecture and reading, but it could also be used in class, in lab, or as group work.

Igneous rock types, identifying igneous rocks

Understanding scale and visualization.

This worksheet walks students through how to use the igneous rock composition chart to identify rock types. Students are shown three different rocks and given the mineral percentages for each. Using the mineral percentages, student build a scale bar using colored segments to show the amount of different minerals. Students can then move their scale bar with the colored mineral segments across the igneous rock composition chart until the boundaries in the scale bar match the mineral field boundaries on the chart. Once the student finds a match, the student can see whether the rock is a granite, diorite, gabbro, or peridotite.

This worksheet allows students to complete this task physically, rather than mentally, and walks them through the process of igneous rock identification based on mineral composition. We find that it also makes the chart more understandable and approachable.

This worksheet uses the sketch-understanding program with built-in tutor: CogSketch . Therefore, students, instructors, and/or institution computer labs need to download the program from the CogSketch website: http://www.qrg.northwestern.edu/software/cogsketch/. At any point during the worksheet, students can click the FEEDBACK button and their sketch is compared to the solution image. The built-in tutor identifies any discrepancies and reports pre-written feedback to help the student correct their sketch until they are done with the activity. Once worksheets are emailed to the instructor, worksheets can be batch graded and easily evaluated. This program allows instructors to assign sketching activities that require very little time commitment. Instead, the built-in tutor provides feedback whenever the student requests, without the presence of the instructor. More information on using the program and the activity is in the Instructor's Notes.

We have developed approximately two dozen introductory geoscience worksheets using this program. Each worksheet has a background image and instructions for a sketching task. You can find additional worksheets by searching for "CogSketch" using the search box at the top of this page. We expect to have uploaded all of them by the end of the summer of 2016.

CogSketch has a gradebook feature that allows instructors to batch grade worksheets using the defined rubric in the worksheet. Once graded, instructors can also open all the sketches and evaluate student work. Instructions are given in the Instructor's Notes.

Download CogSketch: http://www.qrg.northwestern.edu/software/cogsketch/