Sketch why a ball can overhang a football boundary
A ball’s contact with the grass is a small part of its shape. To understand a boundary replay, sketch the entire ball relative to the line rather than watching only its bottom. This paper exercise explores the whole-ball principle without claiming that a television still can supply an accurate official measurement.
Original explanatory diagram. Read the full method and limitations below.
Draw the boundary as a strip
Use two parallel marks to represent the painted line’s width, then shade the playing side lightly. Put a circle beside the strip to represent the ball viewed from above. IFAB Law 9 says the ball crosses a touchline or goal line out of play when the whole ball has passed over it, on the ground or in the air. This lesson isolates that boundary condition; play can also stop for other reasons.
Move the whole outline across
Make three small sketches: a ball mostly on the playing side, one overhanging the outer edge and one entirely beyond it. For each, point to the last part of the outline that would need to clear the boundary. You do not need actual ball dimensions to explore the idea. Label the drawings conceptual, because your circles and line widths are invented. A tidy sketch explains a principle but does not measure a real incident.
Separate footprint from full shape
Now add a small dot at the center of one circle to stand for a simplified ground-contact location. The dot may appear beyond the line while part of the larger circle still overhangs it. This is the visual trap the exercise is designed to reveal. Erase the dot and check the outline again. A suspended ball has no footprint on the grass at all, yet the question still concerns its complete position relative to the boundary.
Read a replay’s limitations
When watching, notice whether the camera looks along the line or across it at an angle. Perspective can make the farthest edge difficult to judge, and a freeze frame may not show the exact crossing moment. Describe that limitation specifically instead of tracing your own authoritative line across a screenshot. Record the official outcome separately from your visual sketch. The conceptual drawing helps you understand what is being judged while leaving the actual judgment with the match officials.
An original illustrative exercise
In an invented tabletop demonstration, a paper circle slides across a thick pencil strip. At the second position its center is outside, but a crescent still overlaps the strip’s outer boundary. The viewer labels this not fully across in the conceptual drawing. At the third position there is a visible gap between the entire circle and the strip. These drawings demonstrate geometry, not a decision about an actual goal.
Questions that come up
Is this also a complete guide to awarding a goal?
No. It addresses only the whole-ball boundary idea. Goals involve additional conditions under the laws, and another offence or stoppage can affect what happens in a real match.
Does the ball have to touch the ground outside?
No. The boundary wording includes a ball in the air. That is why a full-shape sketch is more useful than looking only for a mark where the ball contacted the grass.
References and scope
These sources support the factual background. Examples and exercises are original illustrative teaching material. References do not imply endorsement.
- IFAB — Law 9, ball in and out of play — The whole-ball boundary principle, not a comprehensive guide to every reason play stops.