Teacher Mark Andrew Tripptree, 47, pleaded not guilty in the Launceston Supreme Court yesterday to the charges.

The Crown has accused him of having exposed his penis by masturbating in a public place, in two separate incidents, on the morning of March 31, 2012.

Two women gave evidence for the Crown yesterday that the acts occurred while Mr Tripptree was in the driver's seat of his stationary car in Penquite Road, Newstead, and about two hours later in St Leonards Road, St Leonards.

The defence has denied that such acts ever occurred.

Mr Tripptree's wife gave evidence yesterday and said she had been in the back seat of the car, looking after a young child in a baby seat, when her husband was driving in St Leonards Road.

Mr Tripptree also gave evidence, which continued this morning.

He said that he had been looking for garage sales advertised in a newspaper.

Defence counsel Grant Tucker argued that his client was using a flesh-coloured pen to mark the advertisements, so the Crown witnesses were mistaken.

Prosecutor Patrick Dixon surmised that Mrs Tripptree would not be the first wife, nor the last wife, to lie to protect her husband.

The jury is expected to retire before lunchtime.