You get poison oak from touches poison oak (green, three leaves not hairy leaves) which gives off a black type of oil which stays on your skin or clothes etc..
Also you could get it from an infected individual. To get it that way is if there poison oak touches your clothes or skin within 74 hours of the infected individual getting it.
Or you can get it from saying have a ball go into poison oak and you taking it out of poison oak then playing with the ball again.
If you are wondering how to prevent it keep reading.
Well the most successful way of getting rid of poison oak is as soon as your kids come back from outside tell them to have a warm shower and use 2x the regular amount of soap. And then when they get out of the shower once they dry off wash the towel IMMEDIATELY then wash your hands. Then if you want to make sure that they do not have poison oak tell you child to rash their legs, arms and faces with rubbing alcohol.