Part I: Questions about God, Man, and Sin
23. Q. Did Adam and Eve stay holy and happy?
A. No. They sinned against God.
(Click through to read scriptural proofs.)
Now the serpent was more crafty than any other beast of the field that the Lord God had made.He said to the woman, “Did God actually say, ‘You shall not eat of any tree in the garden’?” 2 And the woman said to the serpent, “We may eat of the fruit of the trees in the garden, 3 but God said, ‘You shall not eat of the fruit of the tree that is in the midst of the garden, neither shall you touch it, lest you die.’” 4 But the serpent said to the woman, “You will not surely die. 5 For God knows that when you eat of it your eyes will be opened, and you will be like God, knowing good and evil.” 6 So when the woman saw that the tree was good for food, and that it was a delight to the eyes, and that the tree was to be desired to make one wise, she took of its fruit and ate, and she also gave some to her husband who was with her, and he ate. 7 Then the eyes of both were opened, and they knew that they were naked. And they sewed fig leaves together and made themselves loincloths.
See, this alone I found, that God made man upright, but they have sought out many schemes.
Scripture quoted from the English Standard Version.
Taken from A Catechism for Girls and Boys found here.