Lesson Enacted: Friday, June 12th, Contact 3
Two students were missing today. One of these students was quiet and often late to
class due to commuting, and the other was lively and excited to learn. At this time
I started to become concerned with the students' motivation perhaps fading. I sent
email messages to them both and only
received a response from the quiet
student.
I went over hybridization and geometry today. I was asking questions like, "how many nonbonding electrons" and "what is the charge," and I was getting some wrong answers. These were issues that the students had mastered before the week without class, and I directly relate their inabilities on this day to the extended time since Workshop 2.
So, the concept of hybridization was somewhat rocky, as I imagine it usually is. I explained s and p orbitals and what those look like and how to count those for atoms. Once they seemed sort of comfortable, I went into explaining the hybridization of methane, then ammonia, and then water. With this came an introduction to geometry. They were getting the sp3 tetrahedral stuff, but then it threw them when I introduced a double bond. It helped when I drew "C" on the board, then made a column drawing the "s" orbital and the three "p" orbitals. Then I would put a bracket around the ones that were hybridizing, based on how many "things" were attached to it. Once I drew this, the students understood the connection to how many orbitals are left over. It should sink in once they actually read the section and once we peer review their assignment on shape.
I introduced the resonance in benzene by drawing the lewis structures, asking the hybridization at the carbons, then asking what's left over and adding in the p orbital. I connected the p orbitals with lines indicating the double bonds reflecting how I drew the Lewis structure. Then I asked them why I connected the p orbitals in that way. I re-drew the structure with the p orbitals and connected them in the alternative way. Next I drew the Lewis structure associated with that. Then I dramatically said, "that's resonance" and we discussed it for a little while. I didn't show any other examples of resonance affecting geometry as I didn't want to confuse them since they were still a little shaky with resonance.
I got a couple responses that were positive.
So, I met with a total of 10 students. I began the session by putting a deprotonated carboxylic acid on the board and having someone draw the two resonance structures. Then I put the deprotonated primary alcohol with the same number of carbons under it and told them that the negative charge makes the molecule unstable (reactive), but that the negative charge is stabilized by the resonance with the first case. Next I added a double bond adjacent to the carbonyl and had someone draw another resonance structure.
Then they started looking over their molecules. I drew dioxin on the board and drew a resonance structure in which one of the oxygens had two double bonds to it and a +2 charge. I asked what the problem with the resonance structure was. It took some guidance for them to understand that the problem was the linear geometry of the oxygen. Initially, the students looked at the charges and where electrons were. I drew CH2=C=CH2 on the board and they still had trouble seeing what I was getting at. Eventually, returning to dioxin, I said, "This carbon has three things attached to it, it's sp2 hybridized with 120o bond angles. Then you have oxygen. Then this carbon is sp2 hybridized with 120o bond angles." They didn't get it, so I added, "What's the bond angle on this oxygen?" Then someone said, "Oh, it should be 180o." With this, the point was made.
15 minutes later I had a pyridine ring in a structure drawn on the board, and I had the student draw a resonance form. He moved the bonds around the ring, and did it okay. Then I drew a resonance form in which the non-bonding electrons from a N in the ring made a double bond and I asked them what was wrong with it. Right away someone saw the correlation and said that the bond angles should be 180o. Then someone commented that they learned resonance first and then geometry, and why did I do it that way. I told the students that a lot of times it's hard to decide which to teach first. I told them that if they drew the "incorrect" resonance structures that I had drawn on the board, that it was fine before they learned about geometry. Drawing one of those structures would have proven that they knew how resonance worked. Correcting it later would prove that they knew how resonance affected geometry. I told her that it's all part of the learning process.
The students started working together on the practice on shape handout. We went over resonance and other related issues with that. I noticed that it's a lot easier for someone to visualize the extra p orbital when the other three bonds are drawn with lines if you draw the connection to how the "z" axis is drawn on coordinate axes. Then they can see what is meant by drawing the orbital at that angle. As I was drawing something on the board a student said, "I kind of like this stuff. I'm starting to get into this!" That was pretty cool. I was there for two and a half hours.
I was correct to fear the extended separation. The students were doing okay in Contact 3, but not operating at the same level they were in the previous meeting. I don't think that they had been thinking all that much about orgo in the past week of no class. When I raised the issue at a meeting, the response was that the students need to be able to deal with a week of not class and still retain information. When they are preparing to take their dental and medical school admission tests, it will have been at least a year since they had taken the classes that will be tested and they will need to retain that information.
I agree 100% with this statement, but belive the it doesn't directly apply to the situation I had in this program. The comparison of retaining the information in the week without class and retaining information for the year before taking a graduate school admissions test is not valid. It's a completely different situation in that when preparing for admissions tests, the students have (hopefully) already learned the material. Preparation for these tests should be, for the most part, reviewing and remembering. During a normal course, students have to adapt to time away from lecture during events such as Thanksgiving and Spring Break. This is also largely different from the situation with this program. The program is only a few weeks long, so a week away from lecture is more significant than in a course that lasts several months during a normal semester. Another significant problem with the separation was that the format of the class changed. Previous to this week, meetings were organized as a Contact (lecture format) on Wendesday with the Workshop (discussion format) on Friday. After the week separation, the format switched to Contacts on Friday and Workshops on Wednesday. The most significant problem with this switching was that the day the homework was peer reviewed was different, affecting when they received graded homework back. In a short program such as this, one wants to give the students every possible advantage, not present them with added situations to adapt to. It is my strongest recommendation that the format of the schedule (both in the days of the week and in the type of format the days take-lecture, discussion) remain consistent throughout the program.
I had the opportunity to help one student with the resonance assignment the day of Contact 3, after class. All of the structures were completely wrong. However, it only took about 10 minutes of one-on-one contact for the student to understand the problems and make corrections herself. The structures had too many bonds on certain atoms, some unaccounted for charges, and incorrectly drawn nonbonding electrons. To help, I made sure that the student drew all the non-bonding electrons in the structure first. Then I asked that the student track the movements of electrons by using arrows. There was a benzene structure in the molecule as well and I asked the student to draw a resonance structure as we did in class. The student did this and then I asked which was a greater resonance contributor, the structure that was just drawn (resonance with benzene) or one with an O with a negative charge and an N with a positive charge. The student answered correctly the one was just drawn. Then I asked which was the greater contributor, the one was just drawn (resonance with benzene), or the originally drawn molecule (also resonance with benzene). She said the original structure. I asked again and kept asking why? After a couple times repeating the questions, the student asked, "Is 'the same' an option?" How exciting. Then we went over two similar structures, but one put the negative on N and one put the negative on O. I had the student think about it from the standpoint of electronegativity, and the student answered this correctly as well.
At first, I was discouraged by the lack of correctness in the resonance worksheet. Then I started to think about the construction of this program that we established. These assignments are not like honors assignments given in the previous classes I have taught. The honors assignments are given in the final stages of learning. Those have had lectures and time to read the material and time to absorb it. For this program, in a lecture given Wendensday, the students have that 1 hr and 45 min to absorb as much information as they can. Then they are given an assignment with only that night and the next day to complete it. If one thinks about it that way, it's really quite remarkable that the assignments are coming back so good. I've broken the process into the stages of learning that they should be going through with the ones that they are forced to go through noted by an asterisk.
1. pre-read the material before lecture.
2.* lecture.
3. re-read the material after lecture.
4.* do the assignment.
5.* review some of the assignment with me in class.
6.* peer review the assigment.
7. re-do/make corrections to the assignment after I have graded it
Technically, 4. shouldn't have an asterisk, but in general, most people completed their work. So, I believe that following this 7 step program will bring the students to a point of proficiency in the material. With the honors assignments, just because of the time issue and the amount of lecture, I believe that those students are closer to proficiency when they actually do the assignment. I think this is a contribution to differences in the assignments between the two programs when they are initially handed in. At this point, I had not been observing extreme amounts of change (with the exception of the practice on properites handout) after the peer reviews, simply because of a time issue. If they had a solid 45 minutes to review the assignment and make corrections, then I believe there would be more change. This observation altered as the program continued and students became more proficient with the material. The latter assignments have many more suggestion on the peer revies sheets as well as changes between the pre-peer reviewed assignments and the post-peer reviewed assignemnt. Unfortunately, there is just not enough time in the program to allow more time for the peer review process. I would rather emphasize number 7 from the list above more and number 6 less at the benefit of teaching more material.
At the review, in a moment of frustration with learning new and difficult material pertaining to resonance and hybridization (they were trying to SEE two cumulative double bonds and how the terminal sp2 orbitals are perpendicular to each other) they were commenting on how they are ever going to learn all this when they take orgo as a class. Someone said, "Yeah, what's this all, like the first THREE days!?!" This demonstrated that the students really have no idea about the material they are learning or the pace. I replied, "It's a little more than that", but then dropped the topic because I don't want to be too encouraging that they stop doing well. The power here is that they have no idea what they are "supposed" to be doing. They didn't come in with preconceptions since most of them have never seen organic chemistry before.
Up to this point, I had heard several comments regarding the biology course, but I had not heard anything about physics at all, which caused me to wonder what the students were doing in that class. So, I asked a couple students what they were doing. The immediate response was, "'sigh', I don't know." Another student said, "I guess physics is just a bunch of equations, and I need read more." Those students communicated to me that the teacher was moving really fast and was hard to follow. They were talking about how, in the previous week, they did "all that velocity stuff" and "Monday they did circuits and stuff." Based on the syllabus, I think the instructor is trying to teach way too much. A more focused curriculum would probably be better for the students.