• 12-15

In continuation of the part two, the students carried out the same exercise for NaCl (adding acid and testing for the gas). they identified Chlorine gas (they were actually ecstatic doing this). They then declared they had identified (finally) the common salt. (I have given them the task of writing out a lab report of their finding. I will be looking out for their inputs under "hypothesis". This is because, in a lab report, this is the area least understood by students.

This is of course based on my earlier experiences with student writing. I would be interested to see whether their hypothesis has moved from being wild guess has moved to informed prediction) I am also planning to discuss their hypothesis in terms of the (explicitly stated) ENV model and make them aware of exactly how they have been using themi.e. to make them cognizant of this process.

However, I have also introduced the next task (taking away the fish). I cut short their celebration by telling them this, " Yes congratulations you can be sure that this is common salt. Halt. All you have actually explored is the chloride part. What if it is a chloride of another metal? For example, Potassium? would you get exactly similar results?"

While some (half the class about 5 students) felt very disheartened. However, the rest (another 5 have started thinking about OTHER chemical properties). I have left them at this point (to undergo a painful deadend kind of feeling). Next week, I want to open up with the same question. I have to introduce new "tools" (tools that would enable them to identify the positive radical in a salt). I do not know exactly how I am going to do it.