These cards are double sided, and you should print a pair per paper, my recommendation is to laminate the pages to protect them. The PDF file is 300 DPI which is more than enough for an A4 page.
The Scratch Cards Were designed as hard copy.
There are couples of reasons for that:
- It's easier to have a card next to the computer, especially for young children, who may not know how to switch windows.
- An on screen version is less comfortable to read
- An online version makes you susceptible to network problems, and you may not be able to access the cards when you need them for class (we all teach computers so we all depend on the to work for us, when they don't it's a problem... ;-) )