where does it come from

I was having a discussion with my4 yr. old grandson today(one of many). he said milk comes from a cow, the farmer puts it in bottles and takes it to the store. I asked him where does hamburger come from? he said The hamburger store of course. It was funny at the moment and then I started thinking of how many things and how many children don't really know where something comes from. Not just meat but dairy products,veges, fruit, nuts, etc. aren't we doing an injustice by not showing,teaching and being a little more self sufficient? Just a thought for the day.