Subject: Freezing water, the 'Mpemba' effect

Hi,
I read in a magazine (Science et vie Junior) that hot water could 
freeze more rapidly than cold water.  Seemed to me that it was 
illogical since hot water had to give away more energy than cold 
water.  The phenomenon was refered to as the "Mpemba" effect, from the 
name of the african student who is supposed to have made the 
demonstration to its teacher.  The name Mpemba might be spelled wrong, 
I read it long ago, but ever since I could'nt stop thinking about it, 
especially when I teach energy transfers in my chemistry class.  Some 
of my students proposed the same hypothesis as you about the density 
of hot water that is inferior than the density of cold water, but it 
did'nt convinced me.  I never could find any confirmation about this 
nor information about "Mpemba" effect.
Can you help me?
Thanks!
Yves

Re: Freezing water, the 'Mpemba' effect