No mass?

Yesterday, on the way home from school i asked each of the kids about their homework assignments.  I like to know what i am up against from the start (especially since John is out of town this week).  Mark had some math which is pretty typical,  Emma had a worksheet or two and to practice spelling.  Jack said he had to study for Science and he had to bring in an object that has no mass.  Mark laughed and almost spewed granola bar all over the van. Mark said, "Jack that's a trick.  Everything has mass."  It just so happens Mark had just taken a test over the exact same material just a week before. 

 The conversation continues..."What!"exclaims Jack.  "How do you know?"  

Mark explains,  "Mass is a quantity of matter that can be measured."

"What's Matter?"  Jack asks.

"Matter is a substance that has mass and takes up space."  Mark continues.

"How can the definition of mass be matter and the definition of matter be mass?  You can't define one with the other it doesn't make sense!"  Jack states confused. 

"What about air?"  Jack asks

Mark states, "What do you put in a balloon when you blow it up?  Air!  See Jack it takes up space."

The light bulb clicks on, "OH!  So when I asked Mr Ochoa, 'what if we cannot find anything to bring in?'  he responded 'your on the right track Jack' that's what he meant!"  

What a lesson in science we had!  I was a proud mama sitting there listening to my boys actually having a conversation, without fighting, yelling or hitting.  My babies are growing up.