VSEPR Theory Lesson Plan

This lesson plan is fairly vague and allows a lot of room for personal preferences and teaching principles.  You could perform this lesson plan utilizing direct instruction and get through this fairly quickly.  However, using visual aids and other electronic methods of explaining this concept would be more beneficial to students.  Additionally, if the school has the resources, using individual model sets with the students is a wonderful tool in explaining the concepts of molecular structure that can be increasingly difficult to visualize in the higher levels. 

In the lesson plan, it states that, "this lesson plan corresponds to objective 1.07 of the North Carolina Course of Study for Chemistry."  It is important that this lesson plan follow the instructional needs of the state standards and it is also extremely important that when finding lesson plans online that they follow your specific set of state standards.  Since they provided you with the information that this is for North Carolina, you can look up their standards and see if you need to add more to the curriculum or perhaps discuss some parts less intensely if not specifically required or if time runs short.

            In the subject of molecular geometry, electronic computer animations are an excellent tool in allowing the students to understand the shape and general view of what the geometry and shapes look like.  Appealing to the visual parts of the brain by giving many computer animations of the molecular geometry can be very helpful in allowing the students to understand the material.  This better understanding can be accomplished by using familiar shapes to describe the molecular orbitals to help the students see what you are trying to explain.  For example, the trigonal planar molecular shape could be visualized by comparing it to a triangle laying flat on its side.

            This lesson plan can also be changed to feature either a mastery model, coping model, or any model that a student would benefit from.  There is not one specific way this lesson plan needs to be taught.  You can breeze through it and make it seem like this is something easy to do and understand, or you can take it slow and spend a lot of time visualizing the structures and shapes of the molecules.  Some students may have a very easy time quickly mastering some concepts of this lesson, but this lesson plan allows you to bring in more abstract concepts about how and why this happens, or you can also just stay basic and continue without the more in-depth topics.  Because of the visual nature of the topic, active learning can easily be accomplished through the use of models.  Another more expensive alternative is to use a chemistry program like SPARTAN which allows students to build their own models on screen and then rotate them and see how the different structures interact with each other.  This may require a trip to the computer lab, but it is a learning experience they will never forget.

 

http://www.chem.ubc.ca/courseware/121/tutorials/exp7A/tetrahedral_hole.gif

            The majority of this material and information will probably have to be presented via an overhead projector or something like a powerpoint or just writing it on the board.  However, this information should be directed at students so that when they make their new scheme for this information they can effectively and properly store it to fit with this radically different geometrical atomic structure.  Most students will have never seen these structures and you would need to make sure that when discussing this that relevance is used, it must be interesting, and throwing in a few comical references never hurts.  In this way, the students are more likely to retain this information and be able to recall it and use it later on in the course and even later in life.

            In the chart that students fill out in class, the orbitals are organized in order of number of bonds, number of unshared electron pairs, and by increasing complexity.  This chart has a few flaws though.  First, the group number column should be omitted as it only creates more confusion when asked what the shape should be based on the group number since there are too many exceptions to this "rule."  Also this sheet does not show the additional forms of VSEPR models that exist.  Perhaps this lesson plan intends to distribute another sheet with more advanced models on it.  By making things clear and concise, students are not only more likely to want to study this sheet, but it will actually be more helpful for them if it is well designed and looks professional.

            Additionally, the handout given to students is outdated and could much more easily be understood by the students by simply making a new handout.  Many students are immediately turned off to these old types of charts and papers that have been photocopied too many times and appear grainy and outdated.  Also the information presented on the handout is poorly illustrated and worded for the students to understand.  Some students may not understand that small symbol that means angle, and unless this is a higher level class most, if not all, of the students will never have seen sigma before either.  You can either tell them what sigma means and why it is used, and explain what the angle symbol symbolizes, or you can just revise this sheet to make it more student-friendly.  If you instead use a modern program to draw the examples, create a new sheet, and use familiar symbols to express these ideas, it will all be very helpful for helping students understand the subject matter when studying or reviewing.  If it makes sense to them, and the tools they have been given are working appropriately, then they will much more easily understand and learn the concepts being studied.

            Similarly the homework sheet also needs reworking.  This sheet has a very poor typeface for chemistry and the molecules the student is supposed to recreate are sometimes very hard to see due to the poor quality of the typeface.  Also the molecules themselves do not look like they should with the subscripted numbers being far too large when compared to the element letters.  There should also be more than 8 problems and then a short answer question.  As the answer key shows, the student can simply answer most of the questions quickly and efficiently simply by referring back to the handout and there is little effective thinking about abstract ideas about the VSEPR theory.  In other words, there is too much of a focus on the structure of the orbitals and not enough study about the reasoning behind why the VSEPR theory exists and is the current model for the structure of molecules.  If students understood the reason behind why this is the current model, it would further their understanding about why we think this is what the molecules look like, and they would better understand how we came to think the molecules form these particular shapes.  This could be accomplished simply by telling them a story about the history of VSEPR theory and have them take notes on parts they find interesting.  In their homework there is also no rehearsal about practical applications of the VSEPR theory which would relate to real life.  An additional worksheet about these subjects is necessary in order for the students to fully understand why we have VSEPR theory and what it means to chemistry instead of just saying this is what the structure is, now draw it a few times.

            By teaching them about the molecule structures, and then helping them fill out a worksheet in class and then giving out homework, scaffolding can take place by initially helping the students in class fill out the worksheet and then giving them homework about what they just learned to "remove the scaffold" and allow them to complete a similar task on their own.  This is a good way to help the students retain this information through rehearsal and replication.  By repeatedly drawing and interpreting what chemicals should have which structure, the students can begin to see what a molecule would look like in real life just by look at the formula of it.

            From the lesson plan:

"Goals

  1. Introduce five common shapes of molecules
  2. Use VSEPR theory to explain geometry of molecules.
  3. Integrate technology into the lesson. "

one of the goals is to integrate technology into the lesson.  However, the only technology I have seen applied here is the possible use of a computer projector.  There are many, many ways to use technology in teaching this subject that are extremely conducive.  By using interactive computer animations and possibly even gif animations images, the teacher can show the students what the molecule looks like without even saying a single word about its structure.   Also the use of computer programs to allow the students to make their own molecules and manipulate them to see and understand the structure can much more easily show them what it looks like than trying to draw it on paper.  Although not necessarily technological, physical models allow students to do the same thing on the computer right in their own hands.  Hands on active learning is extremely helpful in many ways including storage of information due to the relevance applied to it because of manipulating it with their own hands.  Things just piggy-back on one another in this instance.  The other goals are accomplished, but could be better explained as to why we use the VSEPR theory and why the 5 most common shapes are formed and not the more abstract ones or just something random.

Overall this lesson plan was fairly inclusive and attempted to follow the state standards of teaching this subject; and it showed.  Because this only followed the state standards the basic topics were covered but were not very in-depth.  The actual reason VSEPR theory is used was not discussed.  Other possible valence shell electron repulsion theories were not discussed.  Practical real world applications were also omitted.  Some students might leave this lesson wondering, "when will I ever use this in my life?"  If they are going into a science or especially a chemistry background, this is the fundamental concept in all of chemistry that they would need to know.  If not, simply using the techniques in this course to visualize abstract structures can help them in many ways in all aspects of life because they have developed that kind of skill where they can now visualize objects better.  A big problem was the inadequacy of the handouts, homework, and table provided.  They were all outdated and needed to be either remade, or a newer looking substitute found.  Nowadays there are many programs that can draw molecular structures very neatly and there are hundreds of fonts on any basic computer with Microsoft word.   Just making these old fashioned worksheets look like they were written on a new/normal computer will make students more likely to use these handouts and worksheets.  Cheap plastic molecular models and expensive computer programs are not a necessity, but are extremely helpful in giving the students a hands-on experience with the shapes and can help them visualize what they are learning much more easily.  This was a good lesson plan, but needs a bit of updating and a more in depth curriculum to be better.