Since mentioning the Altar rails in our parish Church here, and also the lack of them in Chapel, I have been thinking much about knees.
First, I would like to assure you of the manner in which our boys here receive Holy Communion. We may not have fixed altar rails, but half way down the Church there are pew fronts which serve the same purpose. Between this and the Altar, the pews face inwards, collegiate style, and are use by the choir on Sundays and greater feasts.
So our boys receive Holy Communion kneeling. There are issues here, with a little jostling now and again, but there is not that terrible queue that you get in parish churches. I dread to think what it would be like to do that in a school! With boys pushing and even brushing past each other. It would most definitely not help reverence at the moment of receiving the Lord in the Blessed Sacrament.
I have long been unsure about the queueing practice for Holy Communion from a practical point of view. With the best will in the world one is always going to be more distracted when one has to do something physical, such as walking and something which one cannot do unthinkingly; after all one must think about advancing at a particular pace. Of course this is going to use some mental effort even if it is only a little. Add to that that our minds and thoughts will drift into many different areas (indeed that is what the Devil wants it to do, so that we do not truly focus on the Lord Our God who is coming to us in Holy Communion). If our mind then wanders, and our body is moving, we simply will not be ready when we get to the front of the queue. We can bang on as much as we like about the inner disposition of the soul, and how the person must try to think only of God, but it is unfair if we make the process as difficult as possible.
Similarly this is a grave danger with singing hymns at this point of Mass. It is as if we are saying "Go on, sing along, you know this one, join in the congregation, try to remember the words,carry a hymn book..." Then suddenly you find yourself in front of the Priest, and then you hear in your soul "How bad and wicked you are, because you have not thought about or focussed on the Blessed Sacrament."
To receive Holy Communion and to believe it is hard enough anyway, I do not see why we should make it even more difficult.
I fear that this holy shuffle and constant singing from the moment the Priest descends to administer Holy Communion, is really more than the people can bear. Truly we bind up heavy burdens and lay them on men's backs, as the Good Book says.
It is not good.