開放 and 開ける: access limits and an object to open
Compare rooftop access for students only at lunchtime with a request to open a window, preserving access limits and the difference between permission and completion.
Read who can use the space and when in 開放
開放 (かいほう) here means making a space available for use. “昼休みだけ屋上を生徒に開放している。” says that the rooftop is open to students only during lunchtime.
屋上 identifies the space, and 生徒 identifies its users. Keep the limitation 昼休みだけ rather than treating the rooftop as open to everyone at all times.
Read the object and the question in 開ける
開ける (あける) refers here to opening a window. “暑いので窓を開けてもいいですか。” asks, “May I open the window because it is hot?”
窓 is the object the speaker wants to open, and 暑いので gives the reason. The sentence asks for permission; it does not say that the window has already been opened.
Do not make the two meanings mutually exclusive
開放 can also describe leaving something such as a door open. This comparison therefore does not define availability for use and physical opening as mutually exclusive meanings.
Instead, read the rooftop sentence’s limits on users and time, and the window sentence’s question form. Do not add a meaning of breaking a seal or invent actual facility policies.
Who can use the rooftop, when is it available, and does the window question describe a completed action?
Show the answer and why
The rooftop is available to students only during lunchtime. The window sentence asks for permission to open it and does not state that the action is complete.