Hit the sack
Go to sleep
Can't judge a book by its cover
Can't judge something or someone by its appereance
Be patient
Hold your horses
Sleep like a baby
Have a deep sleep
Small part of something
Drop in the bucket
Something visual says more than words.
A picture paints a thousand words.
All ears
To listen carefully
Something easy
A piece of cake
Raining hard
Raining cats and dogs
Curiosity killed the cat
Being inquisitive can lead to unpleasent situations
Feel nervous
Butterflies in the stomach
Can't change who you are
A leopard can't change his spots.
Important person
A big fish
Study
Hit the books