As a BC, I remember being instructed at First Communion to open wide and the priest would drop the particle in. Everyone I saw take communion did it that way.
Likewise, I've heard these instructions repeatedly over the course of my lifetime in the BC Church. The typical instructions of our priests, at weddings or when we clearly have a number of guests present, normally assume familiarity with Latin Catholic practice (on the tongue, not in the hand) and typically go something like this:
"The Eucharist is given in both species, in the form of a small cube of bread saturated in wine and water, and administered via a small spoon. When receiving the Eucharist, tilt your head slightly back, open your mouth widely, do not extend your tongue and do not attempt to say 'Amen' after you have received. When done correctly, the spoon should not come in contact with your mouth, and thus there should be no personal health concerns."
That said, similarly to the experience of other posters, I have seen many faithful close their mouth when receiving in Divine Liturgies celebrated in our sister churches overseas. I have no idea why that might be the case.