On Friday night, I like to learn with my 4 year old son. We usually learn through a Mishna or two in an illustrated Mishnayot Shabbos, and/or go through that week's or next week's parsha. I want to give him a bekius in parsha and midrashim, so that he has this as a background. And so usually we sit down on an easy chair together with a Mikraos Gedolos, and I tell him the story in English, embellishing from midrashim and meforshim along the way.
While I think that knowledge of midrashim and the famous interpretations is important, I also try to show occasions where there is machlokes, and try to explain why there is machlokes on these particular points, to try to get him to know, from an early age, the distinction between the Biblical text and midrash and commentary; and also to start thinking about the implications and possible connotations of the text.
For example, when learning through parshat Vayishlach, I first told him the end of Vayeitzei, where they met the encapment of malachim, which most understand as angels. Then, when starting Vayishlach, I told him that Yaakov sent malachim to Esav. I explained how malachim means messengers, including human messengers, and that angels are called malachim because they are messengers from Hashem. So then I asked him which type of malach he thought Yaakov sent. (I explained that Rashi said that it meant angels, just like the angels immediately prior, and that Ralbag said that it meant humans.) After a bit of rumination, his determination was that he thought it meant angels. (The specific conclusions are not really important, so much as thinking about the text.)
Last week, we went through much of Vayishlach and Vayeshev (including some age-appropriate glossing over specific details within the story of Yehuda and Tamar). When I got to the brothers casting Yosef in the pit, I told him that "the pit was empty, and there was no water." I added that "there was no water in it, but there were snakes and scorpions in it." My wife chimed in, "some people say that there were snakes and scorpions in it." So I stopped, and explained to him that all that the Chumash says is that the pit was empty, and there was no water in it. But if it already told us that it was empty, why say that there was no water in it? So some people sat that there must have been something else in it, even though there was no water. (Or another way of thinking about it, it was empty only of water.) And so (separate from the Biblical text) they say that there were snakes and scorpions in it*.
He thought about it for a bit and then said, "but Abba, the man with the multi-colored coat was in it!" So that is his explanation of the textual anomaly. There was no water in the pit -- Yosef was in the pit!
Whether or not this works as midrash, it is a nice explanation of the textual anomaly.
* It is a separate exercise as to why the pasuk would go out of its way to say this, on a peshat level, with an answer or two already springing to mind -- the point was that there was no water, such that the brothers were not casting Yosef in there to drown. But not everything needs to be touched on at once.