�y��vlog

Anyone caught with a smartphone in the lower school at Twyford school, west London, has it confiscated for the rest of the term, which senior staff say is such an "unpopular" punishment that it works as a strong deterrent.

Now in Year 13, he thinks the ban in lower school has "probably" helped him to spend less time scrolling social media - but says lots of his friends are still "on their phones all the time".

The girl can be seen stabbing the floor in the lower school hall during the hour before the attack.

The jury also heard a police interview with another pupil, who was in the lower school hall during break time, who said the girl told her she would stab Ms Elias that day.

The pupil witness explained how she saw the girl talking to Ms Elias, when she was told she did not have permission to be in the lower school hall.