Section B Answer all questions in this section. Mark is planning a natural experiment to investigate the short-term effect of noise on classroom performance of school children. He has found a school next to a noisy railway. He has found a school next to a noisy railway. He is going to compare the children before and during a temporary closure of the railway which will stop all trains for two weeks.

Mark scheme

Marking points from the official mark scheme (May/June 2020). The mark or mark type is shown in brackets.

1. [1] The independent variable (IV) could not be manipulated (explanation); [1] as the noise was due to the trains or not (link); [1] Mark could not control when the repairs happened / noise stopped and started (link); [1] so the two conditions of the experiment could not be controlled, they had to be chosen (explanation);
2. [1] Use a questionnaire; [1] asking them if they had been concentrating well (link); [1] e.g. using a question like ‘How well did you work today? 1 = well, 5 = badly (detail); [1] Give them a test in class; [1] e.g. testing them on lesson content (detail); [1] to measure whether they had paid attention (link);
3. [1] brightness; [1] interest of lesson; [1] time of day; [1] how hungry the children are; [1] the number of children in the class;
4. [1] Children will perform better without the trains running (directional, not operationalised); [1] Children's performance will be better when the trains are not running than when they are (one variable operationalised); [2] Children will score more marks on a test during a week with no trains (less noise) than in a week with trains and noise;