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 6 – Experimental Setup: Water

Screen 6 asked students to decide how much water to add to each of the three tanks. Students could choose to supply 600 ml, 300 ml, or 0 ml of water to each tank. Because the amount of water is a factor that should be held constant across tanks in this experiment, a correct response required setting up the same (non-zero) amount of water for each of the three tanks.

Similar to the procedure for setting up the fertilizer, students selected one growth tank at a time and were referred to a tank-specific screen where they chose the amount of water to supply to that tank.

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


Exhibit 48 shows that 35 percent of students, across countries on average, correctly supplied the same amount of water to all three tanks. On average across countries, girls performed better than boys. Among the incorrect responses, 25 percent of students set two tanks to have the same amount of water.