I was a court reporter way back in the olden days before Twitter. Actually, even before mobile phones unless you include the solitary Motorola brick car phone that my office had!
Trials always take the same format.
The prosecution begins with a statement, then start calling their witnesses who they examine on the stand. The defence is allowed to cross-examine these witnesses.
When the prosecution has called all their witnesses, the defence calls theirs. The prosecution can cross-examine these witnesses.
When all evidence has been heard, the prosecution sums up their case in a speech. Then the defence sums up. The defence always goes last as it is considered fairer to the defendant (the jury having their statement freshest in their minds).
Then the Judge/Sheriff sums up the entire case, makes any points of law to the jury.
The jury is then sent out to deliberate. They must try and reach a unanimous verdict but if that isn't possible the judge will allow a majority verdict.
The defendant is under no obligation to take the stand during the defence phase. That is a decision the defence team must make. Usually they don't want to expose the defendant to cross examination by the prosecution.
All my court reporting experience was in England, but the basic format is the same in both countries I believe.
ETA: Personally, I can't see the defence subjecting a 16 year old lad to cross examination.