Measurement applications: surface area and paint

Task goals

• Calculate the area of a rectangular surface (a wall, floor, or panel) that needs painting or cladding, from a realistic scenario.
• Calculate the curved surface area of a cylinder, such as the exterior of a water tank.
• Identify a door, window, gate, or other unpainted region and subtract its area from the total surface area.
• Convert between units of length or area before calculating, and recognise that an area conversion factor is squared.
• Use a paintable area, the number of coats, and a paint's coverage rate to find the total quantity of paint or material needed.
• Round a discrete purchase (tins, sheets, litres converted to tins) UP to the next whole item even when only slightly over, and calculate the total cost to the nearest cent.
• Compare two real paint, material, or supplier options by total cost and/or a non-cost factor, and check whether each meets a stated constraint such as a budget or a free-delivery threshold.
• Write a short, numbers-based justification for a real-world measurement decision.