What’s on the Circumference of a Circle poster
The rule, 4 worked examples, and the mistake everyone makes.
- The circumference is pi times the diameter — and the diameter is twice the radius.
- C = πd = 2πr
- r = 5 = C ≈ 31.4
- d = 10 = C ≈ 31.4
- C = 62.8, find r = r = 10
- Semicircle perimeter = πr + 2r
- Common mistake: C = 2πd → C = πd or C = 2πr
π is the same for every circle — circumference divided by diameter is always about 3.14.
Questions about the Circumference of a Circle poster
- What’s on the Circumference of a Circle poster?
- The rule, 4 worked examples, and the mistake everyone makes. The circumference is pi times the diameter — and the diameter is twice the radius.; C = πd = 2πr; r = 5 = C ≈ 31.4; d = 10 = C ≈ 31.4; C = 62.8, find r = r = 10; Semicircle perimeter = πr + 2r; Common mistake: C = 2πd → C = πd or C = 2πr. π is the same for every circle — circumference divided by diameter is always about 3.14.
- Who is the Circumference of a Circle poster for?
- Circumference of a Circle is filed under 7th Grade (ages 12–13), so it matches what that year asks a child to remember. It is equally useful to an older student revisiting math, and to the parent or teacher answering the question at the kitchen table.
- When should you use the Circumference of a Circle poster?
- Check whether the question gave you the radius or the diameter. That is where it goes wrong. A wall chart earns its place by being glanceable from where the work is happening, so Circumference of a Circle belongs on the wall where that math work actually happens, within glancing distance, rather than filed away.
- What other posters go with Circumference of a Circle?
- Angle Pairs, Area of a Circle and Box Plots sit alongside Circumference of a Circle in the 7th Grade set. Printed together they make a wall rather than a single sheet, which is how a reference set actually gets used.Angle PairsArea of a CircleBox Plots
- Is the Circumference of a Circle poster free to download and print?
- Yes. Circumference of a Circle downloads as a free PDF with no account, no email and no watermark, like everything else in the 7th Grade set. Print as many copies as you like for a home, a classroom, a library or a tutoring group; reselling the file is the only thing the licence rules out.Read the licence
- What size does the Circumference of a Circle poster print at?
- Circumference of a Circle is a vector PDF laid out for US Letter, and prints on A4 with Fit to page — the same file, no separate download. Because every mark on it is drawn rather than photographed, it stays sharp enlarged to A3, A2 or A1 at a copy shop. Colour carries emphasis only, so a greyscale print of Circumference of a Circle loses nothing.Printing guide
Related posters
Charts that sit alongside Circumference of a Circle on the same wall.
Browse every 7th Grade poster, or start from the full catalogue.