On the back cover of your iPad there is a model number. This is found in the small printed type underneath the word 'iPad' towards the bottom of the back cover.
For example: iPad 3 16GB is A1416. If your model number starts with A14… then it is compatible with Drop Scale. For more in-depth details about how to correctly identify your iPad model, check out the official Apple iPad Support page here.
Apple have detailed instructions on how to identify your iPhone model in their support center.
When you have identified what model you have, make sure it's compatible with Drop Scale by visiting this article.