Year 9 Area, Perimeter and Volume Unit
This unit is taught over a six‑week block and as a result, contains a significant number of key facts and formulae that students are expected to remember. All of these essential details are clearly recorded at the front of students’ exercise books for easy reference.
It is important to note that some GCSE-style questions do not explicitly state whether students should use area or perimeter formulae. Instead, students are expected to identify the most appropriate method themselves.
To support students with this type of multi‑step problem‑solving question, particularly those set in real‑world contexts, we are providing the list below. This will help students recognise which strategies and formulae are required and prepare them more effectively for GCSE examinations.
What mathematics is needed to solve the problem: area or perimeter?
What clues can you identify to help you decide?
Jane wants to cover this area with gravel.
She knows that 34 kg of gravel will cover an area of 1 m2
How much gravel does Jane need?
Clues in the Question
- “Jane wants to cover this area with gravel”. The word cover is a huge giveaway.Covering means filling the space inside the shape, not going around it. ➡️ That points directly to area.
- 📐 “34 kg of gravel will cover an area of 1 m²”The unit m² (square metres) is the strongest clue.Square units are only used for area, never perimeter.➡️ If you see ², think AREA immediately.
- 🔢 The question asks: “How much gravel does Jane need?”Gravel spreads over a surface, not along an edge. To know how much gravel is needed, you must know how big the surface is.
➡️ That means you must find the area first.
This diagram shows the floorplan of the room:
Shamus is going to put a border all around the room.
Borders are sold in rolls.
The table gives some information about three types of border.
Shamus is going to use only one type of border.
He has a budget of £150
Which of these types of border can Shamus afford to buy?
Clues in the Question
- The question describes a border being placed all around the room, which means the distance around the outside of the room is needed, rather than the space inside it.
- The measurements provided are the lengths of the sides, and the border is sold in rolls by length, further confirming that this is a perimeter problem.
- Students are also required to consider cost and budget, which introduces a multi‑step problem‑solving element. They must first calculate the total perimeter of the room, then determine how many rolls of each type of border are needed, and finally decide which option fits within the given budget.
Recognising these clues helps students choose the correct method and prepares them for GCSE‑style questions, where the required mathematical technique is not always stated directly.
Mrs Bennett
Maths Department
