Rationale

This lesson is organized in a learning cycle format and utilizes many modes of instruction.  Cooperative learning is used for two phases of this lesson.  One cooperative learning activity is hands-on.  For the �explain/elaborate� lesson, an interactive lecture is the mode of instruction.  Technology is used throughout this learning cycle as well.  It is used in the engage/explore section and in the explain/elaborate section.  The students do most of the work throughout the learning cycle.  They work with their partners, with little teacher intervention during the engage/explore and extend/apply lessons.  Because of the work that they do during the engage/explore lesson, they are able to be active participants in the interactive lecture.  The students are expected to work together to complete the activities and participate in the lecture by providing answers to teacher�s questions and asking questions as needed.  The role of the teacher, therefore, is to provide assistance to the students during the activities as needed and to ask questions to stimulate student thinking. 

For the engage/explore lesson, a computer program called �Atomic Bonding and Structure� was used to introduce the formation of ions and ionic bonding.  At this point, the students are familiar with atomic theory and structure.  The also know that the valence electrons dictate atomic interactions.  They are also familiar with the periodic table, in a very basic sense (i.e.-they know where the metals and nonmetals are and where the s, p, d, f blocks are, etc).  The students work in pairs to go through the Ionic Bonding program and are given a worksheet to help guide them along.  The purpose of having students work in pairs is twofold.  Firstly, having students work in pairs allows for discussion of the concepts.  Secondly the student pair is meant to be a support system for computer use (i.e. they can help each other troubleshoot).  The teacher is not supposed to be passive during this activity, he or she should be circulating around to the students and asking and answering questions.

Now that the student is a little more familiar with ions, the teacher then gives an interactive lecture.  A worksheet that contains �fill in the blank notes� is provided so that the students can participate actively in the lecture.  The lecture is delivered using Power Point.  Power Point was chosen because it was easier to use animations and other visual aids.  For the first example (NaCl), very simple pictures were used (stick figures holding electrons) in order to provide the students with straight forward, easy to follow and discuss prop that is concrete.  Later, animations are introduced to show a more realistic picture of what happens when atoms form ions.  These animations also emphasize very key points such as positive ions get smaller, negative ions get larger, and atoms that lose electrons have a complete octet below the valence shell. Finally, the students work on some examples, one of which is used as a formative assessment.

 The purpose of the third part of the lesson is to continue on with what the animations showed, why ions are a bit more stable than the atoms they arise from.  This activity is also done cooperatively.  This lesson is important because it allows students to further develop the skill of using models and drawings to illustrate chemical phenomenon. This ability is very important in chemistry because they are explaining macroscopic phenomena (like chemical reactions) with microscopic particles.  Being able to represent microscopic phenomena using models and drawings makes it less abstract for students.  The final lesson is merely another assessment. 

All of the lessons in the learning cycle had a common theme, which is visual representation.  The students will get to use many visual  representations of what happens when ions form.  In the first two lessons, the students get to only see different representations.  The Ionic Bonding program uses drawings of atoms, the movement of electrons, and charts to show what happens when ions form.  In the Power Point presentations, the students get to see a much simpler representation of what happens when an ion forms (the stick figures), and then a more �realistic picture� (the animations).  The final step in getting them to understand is then to have them make representations themselves, hence the third lesson on modeling.  These lessons are meant to work together so that the students can develop a more concrete understanding of a very abstract topic.  It would not be effective just to explain this topic to them without visual representations.  The technology that was used in these lessons is meant to provide students with more visual representations. 

Since visual representations are very important to learning chemistry I would like to learn more about using them in other lessons.  Some other things that I would like to look into are molecular modeling (for molecular geometry), and possibly computer programs that aid students in understanding covalent bonding and Lewis structures.  I am also interested in programs that show chemical reactions on the molecular and atomic level.  I think these tools would be very useful in making microscopic phenomena less abstract for students. 

-Written by Tamika A Madison on 19. February 2006