Strike the table with your hands, depending on the sound.
Or just shout out the answer, the wrong score, and the right score.
It is not good to use a mobile phone, and it is unfair to students with poor signal. Another situation is that the respondent will press the phone early, which will also happen to the respondent. It is normal to press the respondent first without knowing the answer, as long as the punishment for not answering is set.
I think it is still necessary to judge by hearing or vision in the case of poor equipment. If possible, you can make your own answering machine, that is, connect several game handles with a computer, and then use the computer to judge.
I don't think the method of table tennis is very good, because if we want to achieve fairness, the initial speed of table tennis should be the same, that is to say, we can't put table tennis into the glass tube directly by hand, because it will produce different initial speeds. Therefore, when we use table tennis, we need a device to start the initial speed of table tennis, and such a device is difficult to make, and even if it is made, its quality cannot be guaranteed.
Simple physical devices, such as table tennis, often turn the behavior of rushing to answer into a kind of ability competition, and this device not only needs the reaction of the contestants, but also needs physical ability problems such as strength.
I have an idea. I don't know if it's good. It might be a little violent. It is similar to the principle of table tennis, but requires players to get close together. That is, the contestants put their hands at the same distance from a palm-sized area, and when they answer first, they quickly reach out to that public area. Whoever has the hand at the bottom is the one who wants to answer most.
But I soon gave up the idea because it was too uncivilized, but this method is better than table tennis: it just tests the reaction of the contestants.
As for my own method of making answering machines with computer controllers such as handles, it's hard to say. I suggest that the landlord find a computer-savvy person among the people around him and work out the best way to make an answering machine according to local conditions.
That's all for now.