https://drive.google.com/open?id=1sAGajwEJ4Ho1GYBKQj3MJQb9-g-QCcfi

Constructive waves are waves that are moving towards each other in the same direction. when they meet somewhere in the middle the two amplitudes conjoin and it makes one big amplitude and after they pass they go back to the way they were before

Destructive waves are waves that are moving towards each other but one amplitude is opposite the other.  When they meet the amplitudes cancel each other out then after they pass they go to the way they were before