Copper coins to keep flowers fresh longer?

Today our son had a friend for sleepover and after playing for a while both of them disappeared into the bathroom with words like "science experiment", "water", "soap", "salt" etc lingering in the air.  Ofcourse it piqued my curiosity and I was listening to their conversation when I can...I heard comments such as " watch out its going to explode", "watch out the rocket is going to go way up, we need to wear protective glasses" and then heard a big sigh with a comment " huh! that was not a good idea, rocket didn't go anywhere...i wonder if we should try with a different soap".  Although I can imagine what they are trying to do and why it wouldn't work, it was also fascinating to see their thought process in this wondering what else might work.  It doesn't matter whether they become scientists when they grow up, as long as they learn how to think outside the box and find other ways to do anything they are trying to do.  Thought I will share that little incident with all of you as I am sure you see that when you observe the kids.  Their imagination and reasoning is something we dont give much credit for.
Here's a small tip I learnt this week.  Anytime I get fresh cut flowers into a vase, they dont stay more than a few days.  Although I heard of things such as adding sugar amongst other stuff might lengthen the lifetime, its too much work:)  So, when I heard that placing a couple of copper coins into the vase full of fresh cut flowers, they last longer.  I started the experiment today and will post after a week or so but...
Why do you think adding copper coins help keep the flowers fresh longer?  post your answers in the comment section and monday I will provide the answer.
have a great weekend and lookout for science around you,
-Sheela

I couldn't post a picture in the comment section so I am adding it here.  Here is a picture of the flowers after 2 weeks in a vase with a few copper coins .  Usually by 2 weeks time, the flowers are all wilted, the water is murky and smelly but as you can see, the water is still clear!.  I believe that's the reason flowers are fresh.
Thanks Melanie for the comment.   I am not yet sure what chemical reaction is causing the water to stay clearer (and with no fungus developing, the pores stay open and the flowers continue to drink water and stay fresh).  I haven' found the correct answer to that question yet as well and am still looking for answers so open to all answers:)

Marshmello fun

Sorry for missing two weeks from the blog.  Time slipped out so fast!  Amongst other things, I got a chance to meet the science teachers in Tampereen Lyseo (high school).  They have both national curriculum and IB program and I am interested in understanding more about what's taught at high school level, what practical experiments do they do in school and what are the challenges they face in doing more experiments.  The teachers were very helpful and spent time discussing about science and showing their lab space and equipment.

For a quick and easy experiment, try this at home.  For Halloween, we happened to get some marshmellows and so we thought of trying an experiment.  When you roast marshmellows on open fire, they do get a bit bigger so we thought of trying it in microwave.  Just take one or two marshmellows and put them in a paper plate and put it on microwave.  Depending on the setting, turn it on upto a minute and watch through the window while its in the microwave.

Post your comments here if possible.  I will add the explanation on friday along with another experiment.
- have a good science week,
Sheela