The ACLS-6 examples all include coloring the entire page, stitching all of the holes until they run into the next stitch and using all the supplies for the flower pot and clover placement activities as well as asking for more supplies when they have not covered the area. Coloring is apt to completely cover the entire page.
To Verify
Stamping a note card is another way of observing their attention to covering a surface. Stickers and felt shapes can differentiate between ACL 3.6 and 3.8. The surfaces may be note cards or placemats, but larger than a placemat is apt to overwhelm them.
To Rule Out
The same supplies can differentiate between ACL 3.8 and 4.0. The addition you need is a sample of a design to follow. Within ACL 3.8, the sample is ignored during the process. Sometimes the sample is glanced at in the beginning and at the end, but the connection to what they are expected to do is missing.
Within ACL 3.8, careful observation is required to distinguish between pseudo goal directed and real goal directed behavior. ACL 4.0 is goal-directed because attention is paid to goal through all or a lot of the process. If I had to draw a line in the sand, I would suggest paying attention to the goal for at least 1/3 of the processing time for ACL 4.0, and less than that for ACL 3.8. Most of the time within ACL 3.8, attention is paid for a few seconds at the beginning and at the end, unless you cue them a lot.