22 Jan 2010

Grading Homework in Inorganic

Submitted by Maggie Geselbracht, Reed College
How do you handle student homework in your inorganic course?


I'm trying a new system this spring (modeled after my pchem colleagues) in which a short problem is due at every lecture, instead of long killer problem sets.

I am tempted to try that in my intro class where I don't normally collect homework!

I have 3 kinds of homework

1)  questions.  usually (not always) textbook problems.  Siimple skill tests.  Not collected or graded. 

2)  problems.  usually hard problems, multi-parts.  typically 2-3 per week.  I grade all of them, but mostly on a +, √, - system.  I usually grade one problem in detail.  I provide DETAILED keys.

3)  pop quizzes.  I give short 1-2 question short answer/multiple choice quizzes in class covering the major points from the last 2 days.  I drop 1/3 of them, so no stress.  Graded basically +, √, -.  I got this idea from the Chronicle of Higher Ed., ("You Will be Tested on This," D. Glenn, June 8, 2007)

here's another interesting article, also from the Chronicle:

From the issue dated April 13, 2007
"Just Scoring Points"

I've tried having 1-2 problems that were due for every class.  In general, I liked it, as it let me see how well they were grasping concepts from class to class.  However, I've gotten student feedback that they didn't feel like with these assignments they were being given enough practice problems.  So, depending on the students, it might also be helpful to give "suggested" problems to try in addition to the short problems due in lecture.  

I randomly collect notebooks and grade them for completeness and a few problems for accuracy. This way I can look at ANY homework I've assigned for the semester. The random part keeps them on their toes and (hopefully) gets them to do the homework.

I assign ungraded problems -thought problems- at the end of lectures in order to prepare students for the coming lecture.  I will also give suggested problems and post solutions.

To evaluate a class of 30 Inorganic I students I break them up into groups of 4 and have 8-10 group homework assignment for the semester.  I grade each group's work and write comments.

I give problem sets.  It's a good workout for my students.

James G. Goll Associate Professor of Chemistry Edgewood College Madison, WI 53711

Here is the link to the article Adam mentioned:


I've tried recommending problems (for no credit) in the past and found that no one other than 1 or 2 extremely motivated students do them. This year I have gone back to giving problem sets due about every other week. They tend to be on the long side. For the most part I like this, but I learned something quite disturbing the other day: my students search for the answers to the problems on the web. (I learned this because they came to complain that "reliable .edu" sites gave different answers to one of the questions I posed. I also learn that some - but not all - of my students immediately search for answers to problems online before trying themselves. ) Have any of you observed this behavior with your students? How common is this?

I haven't directly observed students searching for homework answers on the web yet, but also find that very disturbing.  I would also like to hear if anyone else has observed this. 

Barb, I encountered this the last time I taught inorganic, and it was while teaching MO diagrams. Some of my problems required that students sketch MO diagrams, and I was getting sketches that were "very similar" to those from the web (I could find these sources with a quick Google search) or other textbooks (easily recognizable). In some cases, unfortunately, it was obvious that very little beyond just copying the diagrams was put into the problem. This, of course, led to the oh-so-enjoyable discussion of the honor code.

To address the original post, I pass out ~weekly HW assignments (some questions from the book, some made up, some from VIPEr) and grade them myself. I tried to review all the answers, but this was too time consuming. So I went to just grading several problems from each set and giving a grade based partially on completeness and partially on the graded problems. Answer keys were posted for all problems. 

I have skipped graded homework for the first two rounds of my new Foundations of Inorganic Chemistry course, but students complained that they did not get enough practice with feedback to prepare for exams. So, I plan to use Sapling Learning online homework next time, but I will have to wite a lot of Qs and get a lot of Qs from colleagues.

I handle homework differently depending on the course. All of our freshman chemistry courses use a "studio" model for homework assessment during a one-hour recitation. After being assigned and asked to prepare solutions to 10-15 problems, students are asked to choose five problems for review when the assignment is due. Then five students are randomly chosen and asked to come to the board to present their work. Their solutions are discussed and critiqued by the group. Full credit for participation. No homework solution sets are provided; students learn that they are responsible for finding out the answers (although of course they can ask for as much help as they need, either in person or online via email). Upper-level courses have no recitation and are handled using a variety of models. I tend to assign a combination of homework problems from the book (where they can often look up the answers to check their work) and other problems that I make up. These are reviewed, corrected and returned. 

I used to assign homework from the text or problems I came up with, which I graded for correctness. This last Spring, though, I used Sapling, which has recently added inorganic content. My class (of 2) basically helped me beta test it, and the questions are relatively good quality. I do occasionally throw in some original assignments, though, especially when covering group theory.