Well apparently they introduced the common garden snail - oh thank-you-very-much! They were imported as a food source (no-thank-you-very-much), but the Romans did do a few positives things too, and amongst them, introducing the damson plum, (which originates from Damascus). There you go, you learn something new everyday.
And without wishing to be evangelistic about home ed, that’s one of the great things - the boundaries between something interesting and education blur. We do, as it happens, stick to a 9-3 term time routine, as it suits us - particularly my son who likes everything scheduled (it’s a spectrum thing), but still that blurring affects us, and we might stop what we are doing, such as planting a damson tree, and chat about other things the Romans introduced, and so what if its a weekend, this learning thing goes on all the time.
As for the damsons, we have only planted one damson tree so far, as that is all the nursery had, but my aunt has offered us some treelings (well suckers.. but they should work) so we must get round there with a spade soon.