[I can't mine]

He is using a pick axe.  He is using a MacBook Pro - he has pushed the mouse click pad (equivalent to left clicking) and that didn't work.  He also tried right clicking by hitting ctrl+mouse click pad (equivalent to right clicking).  

 

He is using a pick axe.  When he left clicks it appears the block is mined but reappears instantly.  He never collects anything.  To me it actually looks like debris just shoots up but the block never goes away.  

 

Thank you for any help!

[I can't mine]

I am trying to help my son who cannot seem to mine blocks.  I can't find a list of hot keys to determine if he is using correct key.  Can someone please help?