PRISMS: Phenomena & Representation for Instruction of Science in Middle School

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This is a representation reviewed for the following learning goal:

All organisms, both land-based and aquatic, are interconnected by their need for food. This network of food-based interconnections is referred to as a food web. The entire earth can be considered a single global food web or food webs can be described for particular environments.

Summary

This resource compares a food chain to a food web through text with a link to a pictorial diagram of both a food chain and a food web. It addresses the key idea that organisms are interconnected by their need for food, that these interconnections are referred to as a food web, and that food webs can be represented in diagram form. This is likely to be comprehensible to middle school students.

Limitations:
There is no indication that plants make their own food and form the base of the food web. In the food web diagram, the arrows pointing from the deer and the fox to an insect are confusing, and the organisms are not drawn to scale.

Suggestions to improve effectiveness:
The arrows from the deer and the fox to, what appears to be an insect, need to be explained and/or corrected.

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Detailed Review

Description

The representation depicts a food web and a food chain through a text-based explanation and a link to a pictorial diagram of both a food chain and a food web.

  • Resource Copyright Owner: Sciencebob.com
  • Type of Resource: text/html


Content alignment

The resource addresses the actual substance of the learning goal rather than just the topic.

Explanation

The resource explains with text the interconnectedness of organisms by their need for food. The resource states, "FOOD WEBS SHOW HOW MANY ANIMALS ARE INTERCONNECTED BY DIFFERENT PATHS. EXAMPLE: TREES produce acorns which act as food for many MICE and INSECTS. Because there are many MICE, the WEASELS, SNAKES, and RACCOONS, have food. The insects in the acorns also attract BIRDS, SKUNKS, and OPOSSUMS. With the SKUNKS, OPOSSUMS, WEASELS and MICE around, HAWKS, FOXES, and OWLS can find food. They are all connected!" The text explains the linear path of a food chain and the multiple paths of connections in a food web. A link shows a pictorial diagram of a food chain and a food web and uses some of the organisms that were used in the text as examples. In the diagrams, arrows are used to represent the feeding interactions between and among the selected sets of organisms.

Scope

The resource addresses the indicated part of the learning goal:

Explanation

All [organisms,] both [land-based] and aquatic[, are interconnected by their need for food. This network of interconnections is referred to as a food web.] The entire earth can be considered a single global food web, and [food webs can also be described for a particular environment.]

Sophistication

The resource correctly reflects the level of sophistication of the learning goal.

Explanation

Students are expected to know that the sequence of organisms eaten by other organisms is considered a food web. The text and the diagrams explain these relationships.

Notes for Teachers

This resource does not indicate that when organisms eat or are eaten by other organisms, the organisms that are eaten are no longer available as food for other organisms and will no longer eat other organisms. The user can guide discussions to logically reach this conclusion. This resource also does not indicate that all organisms, both land-based and aquatic, are interconnected by their need for food, nor does it indicate that the entire earth can be considered a single global food web and that food webs can be described for particular environments. The user can help students extend their understanding of food webs to a broader context by supplanting different organisms from different environment in the web and deciding what would come at the end of the arrows in the food web. There is no indication that plants make their own food and form the base of the food web. The user can provide students with information about the role of plants in the food web.

Quality of instructional support

Does the representation accurately represent relevant aspects of the learning goal and/or brings out limitations that are not accurate?

Partial—The representation accurately represents most, but not all of the relevant aspects of the learning goals. It may or may not bring out inaccuracies.

In the food web diagram, there are arrows pointing from the deer and the fox to an insect. If this is meant to convey that deer and fox eat insects, then the arrows are going the wrong way. If this indicates that the insect eats deer and fox, then the insect needs to be identified as a decomposer. Other than these organisms, all arrows on the image point with the flow of food. Students are not expected to know what any particular organism eats. Although particular organisms are identified in the examples used for the food chain and the food web, the focus is on the concepts of a food chain and a food web, rather than what particular organisms eat.

Is the representation likely to be comprehensible to students?

Yes—The representation is likely to make the learning goal comprehensible to students.

The distinction between a food web and a food chain is explained with text and illustrated with comparative diagrams. This addresses the common misconception that food webs are simple food chains. The web diagram shows clearly that food webs are not represented in a cyclical structure, but as a web.

Does the representation make clear which aspects of the real thing are represented and which are not?

Partial—The representation usually, but not always, makes clear which aspects of the real thing are represented and which are not.

Organisms are not drawn to scale. The food web and the food chain diagrams show examples of the interconnectedness between and among organisms. There is no indication that the interconnectedness dynamics illustrated in the diagrams and explained in the text extend beyond these examples into the global arena.

Summary Judgment

Useful with modification

Notes to teachers

This resource explains in a simple, concise, and clear manner the difference between a food chain and a food web, addressing some misconceptions that middle school students have about these interconnections. It does not, however, extend this concept beyond the few examples used on this site. The arrows from the deer and the fox to, what appears to be an insect, need to be explained and/or corrected.

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