J.F.
Take a paper plate and cut it in half. Take another paper plate and make it like a clock. Use the 1/2 piece and cover up one half at a time. It will give them something "concrete" to visualize and understand a half of something. Color it another color if you want. I also write "6" in another color to help make it visual.
Then later, you cut another plate into 4 pieces for quarter after and quarter till. I also use money (quarters) to help explain this.....for kids who are older and understand money.
I hope this helps. :)