He could almost hear the gears turn in his head.

"The wheels are turning in my head as I hear about this."

It was a lot to remember and the words kept turning in his head.

She could almost see the thoughts turning in his head.

I could almost hear the wheels of thought turning in her head.

You could have seen the wheels turning in his head as he came to a decision.

Then he looked around the room, the wheels turning in his head.

If I'm not all turned around in my head, that comes out behind the house.

He was looking at her, and she could all but hear the wheels turning in his head.

I could see the wheels turning in my mother's head.