Interesting visitor

There was an interesting visitor around the school today.

Teacher spotted him on the corridor and he came into class.

We had to use our imaginations and investigative skills to figure out what his interesting piece of equipment was used for.  Can you guess?

We finally found out that it was an alarm tester.  The tester is filled with a can of vapour smoke which causes the smoke alarms to react.  The alarm didn't go off though because the bells were turned off during testing.  Thanks Paul for showing us how smoke alarms are tested!