J loves this kind of stuff.

He finds anything related to geology interesting. Every fourth science lesson, he seeks out an experiment or a concrete example to demonstrate and explain to the rest of us what he has been learning.

 A little like show and tell. 

A little like - we have no clue, fill us in.  

separating the isotopes

graphing the daughter isotopes 

a willing participant

"Do you think he'll let us eat the expirament when he's done?"

".... and this is why the number of decaying isotopes gets smaller as the number of radioactive isotopes gets smaller. "

And we all appreciate your patience, dear.