Student Activity: Predators in Control

Predator–prey relationships are one of the most important biotic relationships in the sustainability of an ecosystem. Predators are the natural controls in an ecosystem, limiting the size of a prey population. Many studies have illustrated that the long-term sustainability of an ecosystem is severely affected if top predators are eliminated. Prey populations increase as a result of the loss of their natural predators and they overgraze the vegetation resulting in ecosystem collapse.

Top predators―including wolves, grizzly bears, sea otters, and alligators―are referred to as keystone species. They are crucial in maintaining and sustaining ecosystem function. For example, on the west coast of Canada the loss of sea otters, a keystone species, has led to an increase in populations of sea urchins and other shellfish which are overgrazing on the underwater kelp forests and destroying the habitat of many different organisms.

This game models the interrelated effects of predator (fox) and prey (rabbit) populations over several generations.

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The Dripper

Hand print

Many children can identify that water exists in 3 states within our natural environment. Understanding that it is the very same water that undergoes changes of state presents far more of a challenge to children in grade 2. The following experiment is simple yet effective in helping children understand changes in state and a rudimentary understanding of the water cycle.

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SciNews to Engage Your Students

What killed the dinosaurs?; frogs’ remarkable tongues; can hydrogen be turned into a metal?; even smarter phones; CO2 and the flow of a major ocean current; interstellar slowdown – just a few of the themes in today’s eclectic collection of SciNews.  Share these stories with your students and get them excited about science.

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Teacher Demo/Student Activity: Iron in Cereal

iron-in-cerealFood labels often contain the word ‘fortified’.  This means that one or more ingredients have been added that are not normally found in that food item.  The purpose is to increase the amount of that mineral or nutrient to serve a dietary purpose.  Table salt is fortified with iodine (to help prevent hypothyroidism, which can lead to goiter which is the abnormal enlargement of the thyroid gland), and many breakfast cereals are fortified with fibre (to improve digestion) and iron.

Iron ions (Fe3+) are essential for the formation of red blood cells.  They are central to the hemoglobin molecule, which is responsible for the transfer of oxygen gas and carbon dioxide throughout the body.  Iron ions are also found in muscle tissue and many enzymes.  Iron is often added to cereal in its elemental form (Fe) because it is more stable and has a minimal effect on flavour.

The recommended daily intake of iron depends on age and gender.  These values are listed in the Additional Resources section, and information about iron content in food can be found in the nutritional facts label on the packaging.

The purpose of this demonstration/activity is to illustrate the importance of proper labeling and identification of substances and the presence and form of iron in breakfast cereals.

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SciNews to Engage Your Students

Maybe not as many new species; peer support helpful; oxygen here earlier than thought; BPA controversy; new engineered material cools roofs; France calling out to scientists, etc. working on climate control – just a few of the themes in today’s eclectic collection of SciNews.  Share these stories with your students and get them excited about science.

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Teacher Demo: Toxic Path: Bioaccumulation

Humans have had a huge effect on the environment by producing and releasing pollutants. Pollution leads to a variety of issues. Some of the better-known pollutants include greenhouse gases, which are the main cause of global warming; acid-producing air pollutants that result in acid rain; and persistent toxic chemicals, which can result in the death of the top predators in ecosystems. Continue reading