Skip to content

Sun Block

Originally appears in the Summer 2006 issue

Purpose: Through emulating the transfer of food energy in a lake habitat, students will gain an understanding of how both non-living factors (sunlight) and other living creatures (producers and consumers) affect an animal’s ability to survive. Students will predict outcomes, and compare scenarios between a healthy habitat and one disrupted by an invasive plant species.

Subjects: science (life systems), health, physical education

Duration: 50 minutes

Setting: gym or field

Materials: 3–6 pinnies (pinafore aprons) of one color, 1 pinny of a different color, 4 pylons, 500 craft (Popsicle) sticks, 4 hula-hoops, whistle, clipboard, pencil, paper, one poster labeled “Sun” and another labeled “Algae” (optional)


European frog-bit is a free-floating aquatic plant native to Europe and Asia and originally introduced to Ontario in the mid 1930s when it escaped from the Central Experimental Farm in Ottawa. It is now found in several lakes and watersheds in southern Ontario and has spread to southern Québec and northern New York and Vermont. It looks like a miniature water lily with heart-shaped leaves and small white flowers with a yellow center. European frog-bit floats on the surface of wetlands and the quiet bays of lakes. It reproduces quickly, forming dense mats of plants at the surface of affected waters. The mats of frog-bit hinder recreational activities, such as boating, fishing, and swimming; potentially hinder the movement of fish and wildlife; and disrupt the food chain by preventing sunlight from getting to plants and algae growing deeper down in the water.

Please enter subscriber password to continue reading  full article.

To view the photo-rich magazine version, click here.


If you are not already a subscriber, please subscribe to read the full article 

This activity is adapted with permission from the draft version of Making Waves! Protecting Ontario’s Aquatic Habitats from Invading Species, a Grade 4 curriculum developed by the Invading Species Awareness Program, a partnership of the Ontario Federation of Anglers and Hunters and the Ontario Ministry of Natural Resources. The curriculum will be available for downloading at no cost from <> by September 2006.