Here are some great online balance scales to use on your SmartBoard.
This scale from iboard is a great site for little ones.
Students simply have to balance animals on the scale.
This scale is a good one for basic comparison of items.
This scale from TeacherLed is great for comparing weights.
Weigh it Up Is a fun activity for practicing balancing weights.
This Bunny Balance game is a fun way to practice comparing weights!
And the Poodle Weigh-In game from Cyberchase is another great practice activity!