You fill the 3 gallon jug up completely, then you pour that into the 5 gallon bucket. Then you fill up the 3 gallon jug again, and pour as much as you can into the 5 gallon bucket until it is full. You should then have 1 gallon of liquid left in the 3 gallon jug, and the 5 gallon bucket would be full. I hope that makes sense!
