The Jal Tara kit has a sample bottle and glass tube which needs to be filled with the water sample. A chemical reagent called Zirchonyl Arilazine is added (2 ml to 50 ml of water) and the glass tube then needs to be shaken and left aside for an hour. The change in colour can be compared to the ones given in the chart by looking at the chart through the test tube and the mg/l of fluoride can be detected and noted down.
This is simple enough for the students to do by themselves, but since my activity involves testing many water samples around the village, waiting an hour to do so might not be the best way to do it :P
The second kit I have is more instantaneous. I thought we could use the one above to test samples in school, go out to test lakes and wells and come back to have results of the water in school the school. In the second kit, a similar process is followed by adding a few drops of reagent to a sample of water. The solution changes colour immediately to indicate the mg/l of fluoride.
In the second post above this, I have explained the aim of the activity and what I would like to do with these kits.