Amoeba and Euglena - h-e-e-e-elp.

See my above post - I use dried grass/hay. Stick a handful in some water and leave at room temp. It takes about 3 days to produce a healthy population of Protozoa. I collect grass cuttings from when the grounds/school field are cut, dry them out & then keep them in a box - they'll last forever! So no need to buy anything in!

The methyl cellulose is just wallpaper paste (use school supply stuff, without any nasty additives) and it's purpose is just to slow the critters down so they can be observed more easily.
many thanks for this. I'll go and hunt the school gardeners down to save me some cuttings :)