CENTURY’s top five recommended revision topics for GCSE maths resits November 2022

Posted on 20th September 2022

Posted by CENTURY Maths Team


The topics below were all in our Advance Information course in the summer term, and these are the questions that students struggled with the most. All of these topics are due to come up again in November in either the Edexcel or AQA papers, or both. We recommend you make these a priority with your students.

You can see the full information from the exam boards on the November exams Advance Information here for Edexcel and here for AQA. 

The Edexcel examiner report for the June 2022 Foundation papers also indicates that the questions on these topics were poorly answered by many candidates. The misconceptions identified below are similar for the cohort wide feedback. Read the full examiner reports here.

For each of these topics we will provide a full breakdown including common incorrect answers and misconceptions we have identified from the answers students submitted. This is 1 out of 5 in our series of topics. Topics 2 to 5 will be published in the following weeks.

Some ideas to build these topics into your teaching

  • Set the recommended nuggets as independent learning using the planner tool on CENTURY
  • Include these topics in your lessons as a starter each lesson
  • Set a mini assessment for students including these topics using past exam paper questions

Combined Events

This non-calculator question was answered incorrectly 92% of the time. The question required students to have knowledge of how to calculate combined events, as well as fluency with calculating with decimals.

Students could have either worked out that the probability of passing was the sum of the probability of passing on the first attempt plus the probability of passing on the second attempt, or they could have found the probability of failing twice and subtracted it from 1. Students may have benefited from drawing a tree diagram to help them tackle this question. 

Method 1: 0.7 + 0.3 x 0.7 = 0.91

Method 2: 1 – (0.3 x 0.3) = 0.91

The most common incorrect answers were:

  • 0.49 - Students have found the probability of passing on both attempts, without appreciating that if you passed on the 1st attempt you wouldn’t take a 2nd test
  • 1.4 - As above but students added instead of multiplied
  • 0.14 - Students have incorrectly found pass, pass but made a mistake on the decimal calculation
  • 0.3 - Students gave the probability of failing the test
  • 14/20 - Students have attempted to find the probability of pass, pass but have added instead of multiplying, and have likely incorrectly added the denominators of the fractions.

The incorrect answers include both conceptual and calculation errors. Students should be encouraged to draw a diagram to help them. It is not necessary to convert the decimals into fractions in this question, and it is not advisable as it opens up more opportunities for error. Although students could have entered 91/100 as the correct answer this was not given by anyone, indicating that any student who chose to work with fractions did not get the correct answer.

To help your students with this topic use CENTURY nugget: Tree Diagrams 6: AND/OR Statements (No Tree Given) (MH46.21)

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