No child is going to be good at aikido. Not really. Parents who expect them to be good are either deluding themselves about what "good" is, or setting an unreasonable expectation.
"Clearly" and "directly" are fine, as long as you, the parent, know what "half-effort, poor concentration and improper mindset" are, particularly in an aikido context. "Immediately"? No. You, the parent, are not teaching the class, and you shouldn't interfere with the teaching of the class. You can say your say when class is over.
Wow! That's the spirit - no kid will be good at Aikido.
Yes, common sense went unsaid: Parent's should not interrupt class. "Immediately" meant "after class as reasonably possible."