Secondary Science - Ecosystems
From Eduwiki
Summary- Chapter 7 Ecosystems – Making Sense of Middle School Science
by Sabiha Dalal
Progression in Reasoning about Ecosystems
Piaget & Leach describe the child’s progression in reasoning about ecosystem...
- Young children (5-7yrs.):
- egocentric – self centered
- think of individual organisms that humans keep
- Ex.) pets, zoo animals, houseplants
- Older students (7-11yrs.):
- think of wild organisms
- anthropocentric – human centered
- have a concept of populations and organisms, but does not have the conceptual understanding of organisms competing for resources.
Nutrition & Energy Flow
Children typically…
- associate food as anything that is edible
- understand that food promotes growth and health
- think of light as food for plants
Children typically don’t ….
- don’t associate starch as food
- don’t see food as “energy”
- don’t truly understand photosynthesis….(think plants get their food from soil)
- don’t understand energy transfer in living things
Food Chains & Webs
- Students understood better when lines were used, as opposed to arrows in showing relationships between organisms.
- Students do not see the big picture or connection between organisms.
- Few understand why animals are so dependent on plants & the crucial role of photosynthesis.
- Many students are lost in the terms “producer” and “consumer” as they have not defined the roles of plants & animals.
- Several students have trouble connecting food webs and see food chains as linear, rather than interrelated.
Communities, Populations & Competition between Organisms
Students have trouble seeing complex relationship in ecosystems. They have a one track mind and don’t realize the interdependence in communities; such as predator prey relationships.
Environments
Students don’t have a complete understanding of the organism and its relationship with its environment. Most children realize that plants need soil, water and sunlight in their habitat. However, the presence of oxygen and carbon dioxide is often forgotten.
Decay
Young children thought dead organisms simply disappear, but could not explain the process. A common belief is that bugs or worms eat the rotted matter, which fertilizes the soil. Older children use bacteria, fungi and decomposers in their vocabulary but can’t clearly define their role. Very few pupils realize the role of decomposers in being natures’ recyclers.
Cycling of Matter through the Ecosystem
Few students have a conceptual understanding of how matter is transferred in an ecosystem. Some believe matter is transferred in a process that starts and stops, rather than continual and undestroyed.
Gas Exchange & Balance
Many students think that air is not used by plants and do not know the connection between plants and animals in respiration. Some students know that plants release oxygen and animals release carbon dioxide but do not see the interrelated process and significance.
Respiration
Young children know that air is necessary for life; however they have a limited understanding of what happens to the air in our body. They just think we inhale and exhale air. Also, very few pupils see a connection between air and food.
Pollution
Young children understand that pollution hurts plants and animals. As children mature, they see how environmental issues are complex and can impact communities on a large scale. Some misconceptions mentioned were:
- “Anything natural is not pollution
- Biodegradable materials are not pollutants
- The oceans are a limitless resource
- Solid wastes in dumps is safe
- The human race is indestructible as a species” (p. 68)
