for anyone about to start pathogens & diseases as a topic in biology.....this is a nice simple prac to introduce the kids to transmission of diseases. The best bit is it's REEEEALLY simple to set up
To make up the solutions needed :
The 'patient zero' solution is just some NaHCO3, 1tsp in 100ml water
The non-infected solution is tap water adjusted to pH 4 with a bit of HCl
For each class, number some small cups/vials so that there's one for each kid. I use little pill cups & write numbers on the bottom.
Pour 10ml of the NaHCO3 into 1 cup (& make a note of which cup number is 'patient zero').
Pour 10ml of the pH4 water into all the others.
After they've done their 3 exchanges, the phenol red turns all infected solutions pink & non-infected yellow.
Cheers,
