Ward's World Activity Guides

Page 2 Purpose: To become familiar with some the diversity of microscopic life found in pond water, such that you have a "touchstone" for later investigations. Introduction: Before beginning focused explorations on various aspects of microscopic biology, it is useful and interesting to simply experience some of the abundance and diversity of life within the microscopic world. In this activity, you will consider the diversity of life found in pond water by searching for specific organisms and by identifying other organisms. You will refer back to this activity and build upon it in subsequent activities. Tips: • Microscope slides dry out. And, exposed to the microscope light source, they dry out faster and heat up. The light source on the Swift Digital Microscope is an LED, or Light-Emitting Diode. It is very bright, at 3 watts, but also relatively cool; this minimizes, but does not eliminate, the drying and heating problems. Thus, whenever organisms are studied, it is important to prepare slides shortly before they are examined and not leave the slides on the microscope for too long. • When students challenge each other, you can have them swap slides; this ensures that the searchers do actually have the organisms they are searching for, though it also precludes any learning related to how common the organisms might be. Preparation: 1. Collect samples of water from a pond or other body of water. Look for water that appears greenish or contains dead and decaying vegetation. Also, as possible, collect samples from different locations and/or depths within the body of water, as different organisms will live in different places. For example, Amoeba are more likely to be found near the bottom of a pond. If you are unable to obtain pond water for any reason, appropriate samples can be cultured or ordered. (Note: Pond water will be used again in later activities; it can be kept, with proper storage and care, or you can gather new samples.) 2. Prepare a slide of pond water. Using the microscope, find several organisms that you are able to identify, and collect images and/or movies of them. Do this for your various samples. You will be challenging your students to identify these organisms for themselves and to look for them on their own slides, so select and label accordingly. 3. Locate hardcopy and/or electronic references with information on the microscopic life found in pond water. An example is the "Pond Life Identification Kit " Web site from Microscopy-UK. Procedure: 1. Have students work in pairs or small teams to prepare and label slides from each sample of pond water you collected. 2. Project an image or movie of an organism in front of the class, have the class briefly discuss what they'd look for in order to identify this organism, and then challenge your students to (a) try to locate one like it in their slides and (b) try to identify it using the available resources. • When pairs or teams think they've located and/or identified one of the organisms, check their find to see if you can confirm this. 3. Challenge your students with 1 to 3 other organisms. 4. Have students complete the activity. Extension: Have your students count how many of each identified species they have on a slide or within the field of view. They can consider the diversity of life in the pond water and how populations differ at different locations. Assessment: Have students submit an image, details on the organism in the image, an explanation of how the organism was identified, and any other information that seems pertinent for several identified organisms. Exploring Microscopic Pond Life (continued) + ward ' s science 5100 West Henrietta Road • PO Box 92912 • Rochester, New York 14692-9012 • p: 800 962-2660 • wardsci.com

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