This can be quite a task, but very possible. I follow a mom on Facebook that has 8 children, yes they are all her own! Two are now adults, married with babies of their own, one is in university and the rest are still at home, the youngest being 3 years old. She has homeschooled them all! She has tough days when she has had to drag them to church in their pajamas, fed them in the car on the way out, had embarrassing moments. I keep telling myself, if she can do it, I can do it! Just with 2, I get days when I feel like running into the hills screaming, but hey the good days far outweigh the bad.
Now when you teach the older kids, let the younger ones do puzzles, play with playdough or blocks. Make no mistake, those little ears are listening and take in every word. We still have days that my youngest daughter brightens up during one of her lessons, proclaiming that she remembers when her sister did that particular lesson! Also involve the younger ones after the lesson, eg. if you were reading about volcanoes, let them make one out of playdough while the older ones write their essays. If they are slightly older let them draw the volcano and write one good sentence about it. Make it fun.