Answer:
What invention lets you look right through a wall?
Canine children.
What has a head and a tail, but no body or legs?
I am long and slim works in light. Has but one eye and an awful bite.
I am whole but incomplete. I have no eyes yet I see. You can see and see right through me. My largest part is one fourth of what I once was.
If you count 20 houses on your right going to the store and 20 houses on your left coming home, how many houses did you count?