Tips on converting virtual bead patterns to physical bead patterns
The virtual bead loom lets you set the dimensions of the grid, so you can make sure the kids restrict their patterns to match. For young children its best to use the large"pony" beads rather than the tiny seed beads. You can purchase commerical looms, or create your own just using a paper plate: cut slits in the curved sides for the string, and use canvas needles since they are larger and not as sharp.
Alternatively
you can use the "lacing" method without any loom. Just go to any
craft store -- for about $10 you can get a bucket of pony beads and several
feet of plastic lanyard string. They also sell kits with both included. You
can then use the technique illustrated at makingfriends.com.
In this technique you fold the string in two, and put each end through your first row in opposite directions. Next row up does the same, reversing the directions. The plastic string is stiff enough to go easily through a short row, say about 11 beads wide. See Molly Suwara's photos for examples. Her lesson plan for the class that created these examples can be found here.