As I've mentioned before, my family is trying to read through the Bible in a year together. I've mentioned how dangerous this is, since there are no shortage of "grown up" topics you have to deal with when reading through the Bible chronologically. Another challenge is that many passages are difficult for me to understand, much less explain to my children.
The other night I ran into one that was particularly perplexing: the passage in Numbers 22 where the emissaries of Balak entice Balaam to go with them to curse the nation of Israel. First, God clearly says to Balaam that he is not to go, but when Balak's emissaries return with what amounts to a "blank check" (or "cheque" to some of you), God gives Balaam permission to go—but only if he speaks exactly what God tells him. Balaam therefore goes with the emissaries, but the next thing we read is that God is angry with Balaam for going! So much so that he sends an angel to kill Balaam.
My children may be used to their father suddenly and arbitrarily contradicting something he has said previously, but it's a little more of a crisis when God seems to do it. I therefore needed a quick source of help for dealing with this difficult passage. Fortunately, I had a couple readily available.
Hard Sayings of the Bible is a massive book which addresses just these kinds of difficult passages. Published by InterVarsity Press, it is included in the Essential IVP Reference Library. This book argues that God tells Balaam that he may go with the emissaries if they ask him one more time to go with them. When Balaam doesn't wait for this condition to be met and voluntarily goes with the emissaries, it is clear that Balaam is less interested in proclaiming God's words as he is in receiving Balak's riches.
The Encyclopedia of Bible Difficulties is a more concise work which also addresses difficult passages. It is included in the Zondervan Personal Growth Bible Study Suite and in the older Zondervan collections. This book argues simply that God sent the angel to give a stern warning to Balaam, since God knew the evil intentions of Balaam's heart.
If you don't have either of these resources, you can always turn to your favorite commentary. Most of the ones I consulted did an excellent job of dealing with the seeming contradiction in this narrative, and each brought out a different element of the story which I hadn't immediately seen.
Ultimately, whichever resource I had decided to consult, it was incredibly easy to open a reference tool pane in parallel to the text and use it to help explain a difficult passage. It enabled us to keep reading the story without getting hung up on the difficulty.