sk, st, sp

SK

100

It is what you wear to school.

mask

200

You sit at this. 

desk

300

You do this when you have a question. 

ask

400

When you take a chance.

risk 

ST

100

Birds build this.

nest

200

You are this when you are good at something.

best

300

You make this when you need to remember things.

List

400

You are this when you are at the end of a line. 

last 

SP

100

Its like a bee.

wasp

200

Another word for holding something. 

grasp

300

When you say words differently, maybe because you are missing some teeth. 

lisp

400

You do this when you are surprised or scared.

gasp