Hannah Packham from the National Union of Teachers spoke to us from outside Haemoor Primary School near Penzance where some staff are taking action over workloads. She says the situation is very rare.
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A teenage boy is also in hospital. Police believe both had suffered adverse reactions to an unknown substance.
Sunshine all day tomorrow and warm week ahead
Lovely and warm with highs of 23 and 24 degrees. Hottest on Wednesday.