Snowboard is a compound sign, just like another favorite kiddie pastime in winter, sledding.
To sign snowboard, first, sign snow. Then mimic a person on a snowboard using your dominant hand formed into an inverted letter V sign, standing on the 'snowboard' made up of your flat non-dominant hand, palm facing down.
Teach your toddler the snowboard sign in conjunction with preparations for a fun winter holiday or weekend on the snowy slopes.
This is a useful flash card taught best in conjunction with sled, ski, skate, and other fun winter-related flash cards.