1. What do the following words have in common?

AND
ETCH
ADDLE

2. What do the following words have in common, other than beginning with CH?

CHAIR
CHORE
CHOOSE
CHIPPER
CHATTER

HINTS:
1. The same three letters can precede each word.
2. It has to do with the first letter and the sound of the words.

Answers:

1. Each word can be changed into a new one by preceding it with STR:

STRAND
STRETCH
STRADDLE

2. The first letter of each word can be changed to an S to phonetically create new words. The new words will have an altered spelling.

CHAIR - SHARE
CHORE - SHORE
CHOOSE - SHOES
CHIPPER - SHIPPER
CHATTER - SHATTER

Credit: Will Shortz in The Puzzlemaster Presents