Greeno Research Team Solution

The research team's solution of the problem of designing assessments had two main parts.

1. We had an interview with each student individually, which was technically a "semi-structured" interview, although it was very close to being just "structured." These interviews were patterned after a standard method in developmental psychology where questions allow students to express different levels of understanding of concepts that the researcher is investigating. We included three kinds of questions.

First, we asked the student to design an animal that could survive in an environment that we described. The animal would live deep in the ocean, and would feed on tiny worms that live in the mud on the ocean bottom.

Second, we asked several questions in which we described some scenario and asked the student to suggest possible explanations of something that happened. For example, we said that a population of deer had been moved into a park, and a year later most of the deer had died. We asked the student to suggest possible reasons for this.

Third, we asked a series of questions about requirements for survival, for example, Does a species need water to survive? why or why not? Would it be possible for some kind of species to survive in a desert? How? Does a species need a warm climate to survive? why or why not? would it be possible for some kind of species to survive where it is very cold? How?

These interview questions were intended to inform us about how the students understood adaptation. We expected that the task of designing an animal would indicate ways in which the students understood relations of "fit" between features of a species and environmental requirements. (It also would be sort of fun.) The scenario questions were intended to provide opportunities for students to offer ideas (a) about the environment, (b) about features of the species, and (c) about their interactions. The requirements questions also gave opportunities for students to consider biological features in relation to the environment.

We asked the same questions in the pre-unit and post-unit interviews. (They were separated by almost five months.)

2. We designed a group task, involving evaluation of alternative environments for a species. We used different species before and after the unit; the pre-unit assessment was about peregrine falcons (the class had read about and discussed that species), and the post-unit assessment was about mudskippers (we prepared background materials, including some text and a video that we excerpted from a Nova TV program). We said that a population of (peregrine falcons/mudskippers) had to be moved to a new habitat, and biologists were considering which of three places to take them. Each of the places was described in a short paragraph, and a picture of a scene in the place was provided. The group received the descriptions/pictures one at a time, and prepared an evaluation of the good and bad features of each habitat. Then they chose the habitat they thought would be best, and prepared an explanation of why it was the one they preferred. These analyses and explanations were written, and during a class the groups gave presentations of their choices and explanations.

Conceptually, these tasks also were intended to give us information about the students' understanding of relations between features of a species and environmental conditions. They were the complement to the "design an animal" question we had in the interview, where the environment was specified and the students considered what kind of animal would survive there. In the group tasks, the species were specified, and the students considered what kind of habitat would support their survival. To work productively on this task, the students needed to know a fair amount about the species, so we had to use a species they had studied (the falcons) or we had to provide some background (which we did with the mudskippers). We were aware that by having different species before and after the unit, our results would not be strictly comparable, but we felt that with this task, the disadvantage of students' possibly remembering their previous solution outweighed the disadvantage of the difference in content.

We were not aware, when we designed these assessments, that the students' learning activities would be organized very strongly by a set of key concepts that the class called "survival needs" (food getting, protection from predators, etc.). It was fortuitous that the group assessment tasks tapped students' understanding of those concepts. In their evaluations, the students attended specifically whether the environments had food sources, predators, shelter, etc.