A very thin film surrounding air
A soap bubble is a liquid film enclosing gas. Soap makes it possible to form films that plain water does not sustain in the same way. Surface tension makes the film tend to reduce its area. For a given volume of air, a sphere has the smallest surface area. This helps explain the approximately round shape of a free bubble, without requiring the opening used to produce it to be round.
The frame’s shape need not remain in the bubble
A film still attached to a frame is constrained by that structure. Once a bubble separates, it no longer has the same boundary. Observe a commercial bubble solution using suitable accessories and follow the manufacturer’s instructions. Keep the liquid away from mouths and eyes and clean spills that could make the floor slippery. The aim is to observe shapes, without mixing household chemicals or looking for harsher recipes.
Not every bubble looks perfectly spherical
Wind, contact with surfaces, motion and other bubbles can deform the film. A bubble attached to another shares an interface, so it no longer resembles an isolated sphere. Do not select only photographs that confirm the rule. Compare different examples and identify what was touching the film. A physical explanation must consider the observed conditions instead of treating each departure as an experimental failure.
Use a simple comparison to ask better questions
Record whether the bubble is free or attached, its approximate shape and what happens before it bursts. If comparing sizes, keep the surroundings similar and avoid deciding from one attempt which accessory works best. This is exploratory observation without controlled measurements. The water photograph in this article is only illustrative. Explore the referenced Exploratorium activities to learn more about surface tension, while distinguishing the demonstration from your interpretation.
