How to use God's signs to learn lessons?

God sends Egypt signs and plagues to display his power and convince Pharaoh to let his children. Read Exodus 7:8-13. What should be clear to Pharaoh in this initial sign from God?

(Note: The snake was the emblem of divine majesty in Egypt and could be seen in the image of a cobra on Pharaoh's crown. Wadjet, the cobra goddess, was protector of the Pharaoh. The Hebrew used here, tannin, can also be translated “crocodile” or “dragon,” and the Pharaohs identified themselves with the strength and power of the crocodile god, Sobek.)