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

A Mobile Food Chain

Grade 4: Life Systems

Contributed by: Catherine Little

Mobile…an artistic Science & Technology activity that’s sure to have them hanging from the ceiling!!!

  • Plants and animals are interdependent and are adapted to meet their needs from the resources available in their particular habitats.

Inquiry Skills Used

This is a research activity using various primary and secondary reference sources.


Safety Considerations

Students should be cautious when using sharp objects such as scissors.  Teachers are reminded to use only round tip scissors.



In every ecosystem, many food chains exist.  The flow of energy from one organism to another is essential to maintain life.  Since all energy starts with the sun, the flow of energy would look something like this:

(sun      [insert arrow]   » producer      [insert arrow]    »  consumers  herbivore(s)     [insert arrow]    » carnivore(s)    [insert arrow]       » top carnivore).

Students could investigate an ecosystem of their choice and design and build a model of the ecosystem.

What You Need

  • Scrap paper for planning
  • Bristol board for final product
  • Crayons, markers, and/or paint
  • Single-hole punch
  • Round tipped scissors
  • 1 metre of string/yarn

What to Do

  1. Start by writing the food chain down in words. Begin with the sun and end with the top carnivore.
  2. Instruct students to sort the pictures into groups according to trophic level: producers, herbivores (primary consumers), carnivores (secondary and tertiary consumers), scavengers, and decomposers.
  3. Sketch a picture/silhouette for each part of the food chain beside each word.
  4. Make a full-size outline of each part of the food chain on separate sheets of paper. The top carnivore should be the largest (i.e., each link in the chain should be smaller than the next).
  5. Trace the largest (top carnivore) silhouette on the Bristol board and cut it out.
  6. Centre the next largest silhouette on the silhouette of the top carnivore to ensure each link in the chain is progressively smaller. Trace it and cut it out.  Continue with each link in the food chain until the sun is done.
  7. Using a single hole punch, punch one hole on the top and one on the bottom part of each silhouette. Students may choose to add details or colour to their silhouettes at this point.
  8. Assemble the mobile by using the string to connect each silhouette.  The sun should end up in the middle of the mobile. The largest (top carnivore) should end up on the top and the producer near the bottom.
  9. Extra string can be attached to the top of the mobile to suspend it from the ceiling.
  10. The mobile may have several branches should the student choose a complex food web.

Mobile with sun

Where to Go from Here?

Students may choose to write a story about how these animals are linked in this particular food chain or they may be directed to make a mobile out of more solid materials.  If you have the training and access to a shop, the mobile may be made out of wood.

STSE Links

In Saskatchewan, there is a bounty for coyotes.  The coyote is a top carnivore.  If the number of coyotes were reduced by 50%, what would happen to the food chain and the environment?  Would the environment be overrun with prairie dogs?

How does this apply to the seal hunt in Newfoundland?  The top predator, humans, stopped killing baby harp seals.   Will this affect the fish stocks in the Grand Banks of the Atlantic Ocean?

Cross Curricular Connections


  • Prepare jot notes from a specific point of view in a debate about how development is affecting natural habitats in your community, and what is being done to protect them.
  • Write a fairy tale depicting wolves (or other commonly demonized animals) as good rather than evil, which promotes actions for preventing extinction of animal species.
  • Write science journal entries with labelled drawings to describe and record observations of, changes in, and modifications made to a living habitat.


  • Data Management: Examine habitats and use the observations to create charts and pictographs.
  • Patterning and Algebra: Look at the changes in habitat due to light, etc. in terms of patterns.

Visual arts

  • This activity also links to Visual arts with the creating of a three-dimensional work of art that depicts a specific theme.

Credit Where Credit is Due

This activity was suggested to me by my colleague, Sandy Szeto  (Science Teacher, TDSB), who adapted it from 101 Science Surprises: Exciting Experiments with Everyday Materials by Roy Richards.