Sentence:  It is suggested that the child pray only the "fardrak'ats" at this stage. He can keep adding the "sunnah rak'ats" from the time he has all the <WSD>"fards</WSD>" completed—that is, from his seventh birthday—so that by age ten he has the entire "salat", <WSD>"fards</WSD>" and "sunnahs", complete. 
Meaning of the word marked with <WSD> tags:  A commandment from Allah that a Muslim has to fulfil; a religious duty or obligation.