"I don't have any homework tonight" -

When I was a kid, I could get away with this often. I was one of the oldest kids in my grade (up until 9th grade when I skipped), so I could handle the workload a lot better than the others. But, inevitably, I'd mess something up, and forget an assignment. No worries, I'd tell myself. I'll do it tomorrow. Mom'll never know, and I'll be ridin' my bike down Main St in no time! She was none-the wiser. By the time report cards came out, I had patched up my grade with extra credit assignments and a little extra studying for the tests.
My kids also have tried this. But, in this era of technology, I can spy on them. The school posts all the homework assignments each day. They also post the gradebooks, with all late assignments noted.
They will occasionally tell (lie to) me, and say they finished it in class. Again, I'm on to them! They don't realize that I've studied the ancient art of face-reading. With #3, I can tell by that little twitch in the space betwen his eyebrows. #2 doesn't realize that she blushes when she lies. #1 has a curious white spot that appears beneath his nose when he lies. #4 looks all crazy-eyed, rolling her eyes up to the ceiling, screwing her mouth up into funny shapes, and wiggling her feet like a Rockette on speed. She hasn't practiced much.
How do you know when your kids are hiding their homework?