Agree. Asking questions in a class of 250 students is counter productive. But, here in India, it's against regulations in many colleges to have classes larger than 60 students. So, perspective :)
taught 300 students in Kabul, Afghanistan at one go (English Class) - what we did was we had PowerPoint, we had a microphone (connected to a mixer and JBL speakers) - and everyone had a sheet so they can follow the lessons, even had think-pair-share (using the PowerPoint as prompts) - had 5 of these classes going at the same time in Kabul University and 1 at the Kabul Polytechnic simultaneously. So you could ask 300 students all at the same time if you set it up properly :)