In the piloting the students' responses to the task "Area" from diagnostic test 1 can be divided into 4 categories.[br][br][list=1][*][b]Graph-as-picture error[/b][br]Some students made a graph-as-picture error and reasoned their answer just with the shape of the graph. A typical answer was:[br][i]Because the drawing at the top looks exactly like the on I have circled.[/i][br][br][/*][*][b]Graph-as-picture error[/b][br]Some students already argued with the area but they still took the shape into account. Typical answer: [i]Because the area increases and then stays the same.[/i][br][br][/*][*][b]Correct answer[/b][br]... but wrong reasoning showed that the students did not interpret the diagram correctly.[br][br][/*][*][b]Correct answer[/b][br]Some students chose the correct diagram with an explanation as follows: [i]Because the grey piece is getting bigger[/i] or similar answers.[br][/*][/list]