Compare the motion of three ducks. Which duck was moving at the lowest speed?

 - a duck that moved 430miles east in 10hours
 - a duck that moved 525miles north in 10hours
 - a duck that moved 555miles north in 10hours
Look at the distance each duck moved and the time it took to move that distance. The direction each duck moved does not affect its speed.
Notice that each duck moved for 10 hours. The duck that moved 430 miles moved the shortest distance in that time. So, that duck must have moved at the lowest speed.