The other day my son pulled out a pot and some measuring cups. He filled the pot with water and began to compare measurements.  I asked him questions like; “how many 1/8 cups does it take to fill a 1/4 cup, and so on.  He would guess then fill.”  Before hand I also explained that the bottom number of the measurements (ex. 1/8) tells how many it would take to fill 1 cup.  Then I would ask things like  how many 1/3 cup will it take to fill 1 cup?I think we will have to try measuring spoons next.  He had a lot of fun and that is what is important.