Hidden Amplifier for a Galvanometer

We often do demonstrations at local schools that require the use of a sensitive galvanometer. For example, we show that a thermocouple responds to warm fingers and will respond with opposite polarity to cool water. In years past we brought along a Pye galvanometer, which had adequate sensitivity for the purpose but which suffered from drift due to ambient temperature changes (cold car to warm classroom) and slow response time. There are of course many digital instruments available with adequate sensitivity, but for a classroom setting with 20 to 30 itchy children, an analogue device is preferable to a fluctuating digital output.