I wonder why zippers have teeth and other questions about inventions

I wonder why

I wonder why (New York, N.Y.)

I wonder why planes have wings : and other questions about transportation

Planes have wings.

I wonder why

I wonder why (New York, N.Y.)

I wonder why soap makes bubbles and other questions about science

Soap makes bubbles.

I wonder why.

I wonder why (New York, N.Y.)

I wonder why spiders spin webs : and other questions about creepy-crawlies

Spiders spin webs

I wonder why

I wonder why (New York, N.Y.)

I wonder why pyramids were built : and other questions about ancient Egypt

Pyramids were built

I wonder why

I wonder why (New York, N.Y.).

I wonder why snakes shed their skin and other questions about reptiles

Snakes shed their skin and other questions about reptiles.

I wonder why (New York, N.Y.)

I wonder why volcanoes blow their tops and other questions about natural disasters

I wonder why

I wonder why (New York, N.Y.)

I wonder why penguins can't fly and other questions about polar lands

Penguins can't fly

I wonder why

I wonder why (New York, N.Y.)

I wonder why the dinosaurs died out : and other questions about extinct and endangered animals

Dinosaurs died out

I wonder why

I wonder why (New York, N.Y.)