Don't eat the sand

As a teacher of 7 and 8 year olds, I am used to being asked to explain...well, life and its many mysteries.  Yesterday Merrill and Shayla were having  a heated argument and finally they turned to me to settle it.  

"Mrs. Newkirk, when you put a magnet in the sand and it is covered with that black stuff, that's lead poisoning isn't it?  Shayla says it's not, but I say it is.  Who's right?"

It took a minute or two of sorting through context, black stuff? magnet? sand?.  Finally I think I understood.  "The black stuff that sticks to the magnet when you put it in the sand is iron, not lead."  

"But is is still poison, right?"

"No, actually iron is good for you, it makes your blood nice and red...(quick thought flips through my head) but that doesn't mean you should eat sand...it is dirty and has bacteria, so even though it is not poison, DON'T EAT SAND!"

*****

Aiden and Emma spent the night last night.  They were very good, slept all night, but Lacey went to the hospital in an ambulance late last night.  The last I heard was a possible kidney infection or stones...