When Jonas tosses the apple to Asher, he sees the apple change.  He is beginning to see the color red.

But suddenly Jonas had noticed, following the path of the apple through the air with his eyes, that the piece of fruit had—well, this was the part that he couldn't adequately understand—the apple had changed. Just for an instant. It had changed in mid-air, he remembered. (ch 3)

The moment when Jonas is playing with the apple is one of the most important ones in the book.  Jonas is tossing an apple to Asher to strengthen his hand and eye coordination.  He notices something funny about the apple, but doesn’t realize that he is seeing it change color.  No one in the community can see colors of any kind.  The fact that Jonas sees the color red first is significant.  It is the Capacity to See Beyond, and red is the color of passion or emotion.  Jonas is beginning to feel.