I got the samples from a biological supply company (like Carolina). They come in a water solution so all you need to do is put a drop on a slide with a cover slip. For the yogurt culture I mixed a small amount of plain yogurt with water and put on a slide with a coverslip. We use microscopes that have powers of 4x, 10x and 40x.
The chart provided for student note taking was helpful. Very basic info, but it was just enough to follow-up an inquiry introduction lab with living organisms. Diagrams used in PPT were too small to see the labeled structures.