Findings from the TIMSS 2019 Problem Solving and Inquiry Tasks

Ina V.S. Mullis, Michael O. Martin, Bethany Fishbein, Pierre Foy, and Sebastian Moncaleano

Chapter 4: Science Grade 8

Pepper Plants

Screen 13 – Evaluate a Student’s Experimental Setup

The final item in the Pepper Plants task addressed another aspect of students’ understanding of experimental designs. Students were given an experimental setup where three tanks have the same amount of fertilizer, but Tank 1 has half Fertilizer A and half B, Tank 2 only has Fertilizer B, and Tank 3 only has Fertilizer A. When asked what comparison could be made using the setup, the students needed to recognize the correct answer: the effect of adding Fertilizer A or Fertilizer B compared to the effect of adding a mixture of the two fertilizers (option B).

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Maximum Score Points: 1
Content Domain: Biology
Topic Area: Ecosystems
Cognitive Domain: Reasoning
Science Practice: Generating Evidence


Exhibit 54 shows that eighth grade students performed relatively well on this item, with 59 percent selecting the correct response on average across countries. There were essentially no performance differences between girls and boys, on average across countries.