Ex 10:1 Now the LORD said to Moses, "Go in to Pharaoh; for I have hardened his heart and the hearts of his servants, that I may show these signs of Mine before him,

2 "and that you may tell in the hearing of your son and your son's son the mighty things I have done in Egypt, and My signs which I have done among them, that you may know that I am the LORD."

God was thinking of the next generation of Israelites. He did what He did so that these Israelites would have stories to tell about how great their God is. That He is the LORD. Telling children Bible stories is God's will.