1. What do the following words have in common?

DIRT
BARE
HAWK
VALOR
WANDER

2. What do the following words have in common?

AIR
ARE
OAT
OUT
AUNT

HINTS:
1. The first letter of each word can be replaced by the same three letters to make new words.
2. Each word can be preceded by the same two letters to make new words.

Answers:

1. The first letter of each word can be replaced by SQU to make new words:

SQUIRT
SQUARE 
SQUAWK 
SQUALOR 
SQUANDER 

2. Each word can be preceded by FL to make new words:

FLAIR
FLARE
FLOAT
FLOUT
FLAUNT