Grade 9 Vector Problems

September 1, 2021

Grade 9 vector problems tend to be challenging questions on a higher GCSE exam paper. They often require students to understand ratios, set up and solve a pair of simultaneous equations and have excellent algebraic notation skills. For these reasons, I make sure students have lots of exposure to vector problems as part of their exam revision.

I posed this question to my most able Year, 11 students, last half term as part of an afterschool revision class.

Grade 9 Vector Problems

You can view this question in the grades 8 and 9 revision lessons.

We began sketching the diagram and noting the given facts. Next, we discussed possible routes that would take us from O to Q or Q to M. I encouraged students to mark the paths using a highlighter before writing any algebra. This way, they would have a picture to refer back to when algebra became complicated.

The majority of the class chose to work out the vector OQ rather than QM. Either way, it was essential to identify the vector as a proportion of the straight line OQM. I encouraged students to label the proportion as ‘x’, which was more familiar than λ.

Setting up Simultaneous Equations

Most of the students were able to work out both vectors from OQ in terms of a and b. However, some students needed help to set up the two simultaneous equations by equating the a and b terms. Setting up the equations was quickly addressed, and everyone chose to use the substitution method rather than elimination to work out the two proportions.

Grade 9 Vector Problems

Overall, this question took about 30 minutes to work through from start to finish. Again, I encouraged students to work together throughout the problem, with me providing 1-2-1 support.

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About Mr Mathematics

My name is Jonathan Robinson and I am passionate about teaching mathematics. I am currently Head of Maths in the South East of England and have been teaching for over 15 years. I am proud to have helped teachers all over the world to continue to engage and inspire their students with my lessons.