The “sons of God” were the godly descendants of Seth. The “daughters of men” were the ungodly descendants of Cain. The Nephilim were giants intellectually and physically.

(1Jn 3:10) You can tell God's children from the devil's children, because those who belong to the devil refuse to do right or to love each other.

Gen 6:5
The LORD saw how great man's wickedness on the earth had become, and that every inclination of the thoughts of his heart was only evil all the time.
What a condemning verse...every inclination and evil all the time.

Gen 6:6
The LORD was grieved that he had made man on the earth, and his heart was filled with pain.
He was displeased in the very center of His being.

And so God sent the flood.

Scripture says that Noah was blameless? Noah was not without sin. It means he sinned but was not held to account for his sins.

Did Noah and Mrs. Noah only have the three sons or did they have other children? Seems that there were lots of years before their births for Mrs. Noah to bear many, many children. And yet, only three were saved from the flood. What does that say about the other children they may have had?

Noah took two of every unclean animal and seven of every kind of clean animal. The animals came willingly to the ark.

Gen 7:11
In the six hundredth year of Noah's life, on the seventeenth day of the second month-- on that day all the springs of the great deep burst forth, and the floodgates of the heavens were opened.

The floodgates of heaven opened when the heavy water vapor above the earth (the canopy) fell. Water trapped inside the earth's crust gushed out when the crust of the earth was broken by earthquake activity. See the Creation study for more details.

When Noah sent out the raven it "kept flying back and forth". Seems as if the raven didn't return to the ark, but just kept flying. The waters had not yet receded so was the raven feasting on dead things that had floated to the surface?

Notice when the animals came out of the ark they came out in an orderly manner…one kind after another. It wasn't a stampede. Wonder of they came out in alphabetical order? Aardvarks first???

The first thing Noah did when he left the ark was to offer a sacrifice to God. Look how God reacted. … “he said in his heart….” . And God was pleased with Noah's sacrifice.

Gen 8:21
The LORD smelled the pleasing aroma and said in his heart: "Never again will I curse the ground because of man, even though every inclination of his heart is evil from childhood. And never again will I destroy all living creatures, as I have done.

What a great illustration of God’s mercy and grace. Even though every inclination was still evil.

Before the flood, animals were not afraid of man. After the flood they were. Why? The animals were now allowed by God for food for man. The animals had reason to be afraid of man.

Why did the rainbow make such an impact on Noah and his family? Why did God use the rainbow as a sign? We see rainbows all the time. Could it be that the canopy that covered the earth was the reason? Could it be that they had never seen a rainbow before?

Why did Noah curse Ham’s son? It was Ham who did a disrespectful thing to Noah, yet it was Ham's descendants who will suffer the consequences.

This is a classic example of how when we sin, it often affects more than just the sinner. Other people often get hurt in the process.

Look back at Gen 6:6. Shouldn't that make people want to everything we can to keep from filling God's heart with pain?