Farm Investigation
Screen 13 – Microscope Pictures
On this screen, students are shown microscope pictures of the hair from the garden and of the cow and goat hairs, and asked to identify the animal whose hair matched the hair from the garden, describing two things from the pictures that helped them make their choice. This item requires students to use their observational skills to provide evidence leading to a conclusion.
For full credit (2 points), students had to identify the cow and describe two of the three characteristics of the hair—texture/smoothness/scales, thickness/size, or color/pattern. Students correctly identifying the cow but describing only one of the characteristics were awarded partial credit (1 point).
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Maximum Score Points: 2
Content Domain: Life Science
Topic Area: Characteristics and Life Processes of Organisms
Cognitive Domain: Reasoning
Science Practice: Working with Data; Answering the Research Question; Making an Argument from Evidence
Results
As shown in Exhibit 25, only 21 percent of students, on average internationally, achieved full credit by correctly selecting the cow and providing two correct characteristics of the hair. However, a further 31 percent achieved partial credit by selecting the cow and providing just one characteristic. Girls performed better than boys (24% vs. 19%, on average internationally).