In world war 1 did they use hand grenads?

Yes. The Germans used grenades that looked just like the ones they were still using in WWII, a stick grenade, sometimes called a "potato masher". It looked like a can of soup with a stick attacked to the bottom. The stick was a great idea, it gave leverage and you could throw them far. The bursting charge of the German grenades was larger than allied ones as well. Allied grenades mostly looked like a Baseball.