Rabbit was sitting in a bush counting the spots on ladybugs and told Donkey to be quiet so he wouldn't disturb him. When Donkey asked what Rabbit was doing, Rabbit explained he was counting the spots on ladybugs and that some have more spots than others. Donkey was surprised to learn this fact as he knew many things but not this.

13. And then he saw Rabbit, sitting quite still in the middle
of a bush. “Shhhh”, said Rabbit when he saw Donkey.
“I was worried about you,” said Donkey. “What are you
doing?”
“I’m counting the spots on ladybugs,” said Rabbit. “Did
you know that some have more spots than others?”
“No,” said Donkey. “I didn’t know that. I know a lot of
things but I didn’t know that. Le me see.”