Samuel Orola, a pupil at Tolworth Infants and Nursery School in Surbiton, collapsed while playing with friends in September last year.
One of his friend's told the inquest he had attempted a 'roly-poly' on the adventure playground's climbing frame but appeared to bang his mouth.
Paramedics attempted to resuscitate Samuel for 40 minutes before taking him to Kingston Hospital where he was pronounced dead.
A pathologist told West London Coroner's Court that Samuel may have damaged a nerve in his neck while on the climbing frame, which triggered a cardiac arrest.
A verdict of accidental death was recorded.
After his tragic death, Samuel's family released a tribute which said he "touched everyone's life in a very positive way".
In a statement, Samuel's family said: "Following Samuel's tragic death at school yesterday, we would like to thank everyone for their support and good wishes.
"We will certainly never forget the happy times we shared with him and pray his soul rests in perfect peace.
"This is obviously a trying time for the family and we appeal for privacy to grieve."