If you use a straw, place one finger over the end of the straw and lower the other end into the culture to the level you want to sample. Lift your finger just long enough to obtain the sample and then lift from the jar. You can purchase pure cultures from a science supply house. But, the students seem to have more fun obtaining and growing their own cultures. Make sure students have had experience labeling parts of protozoans before starting this activity.
Protists are one-celled organisms.
Have students put a drop of pond water on a microscope slide. Cover the drop with a cover slip. Put the slide on the microscope stage. Focus the microscope, using the techniques discussed in a previous lesson. Have students draw on a piece of paper what microorganisms they are able to see.