He walked back and forth. ✬

He shook his head back and forth. ✬

Swing your arm back and forth. ✬

Tom and Mary tossed a ball back and forth. ✬

Tom kept walking back and forth. ✬

Tom paced back and forth. ✬

A man I didn't know was walking back and forth in front of my house. ✬

Tom is pacing back and forth. ✬

Tom rocked back and forth in his chair. ✬

Tom was nervously pacing back and forth. ✬