I dunno what student of what age group you are talking about. But promoting competition is the best way to get the attention of all students according to me. I was recently researching about the same question as yours but for students of lower grades and found that encouraging them with a small gift would get them involved. It doesn't matter what gift you are gonno give.But all that matters is the amount of hype you create for it. You can just start a competition like ,"The one who is gonno answer all questions that I ask will get something". That something can be as small as a pencil but there is an inherent urge to get it.
For small children I suggest you can gift them with squishies.
But just ensure that the gift somehow goes to the less-bright ones too!