A Holder of temperature sensitive elements

A Holder of temperature sensitive elements can best be used in an experiment of a flow in liquids, where it would be very difficult for a teacher to perform the experiment by himself. A teacher has to be able to hold the holder with a test tube and simultaneously set two temperature sensitive elements in the right height to be able to see a temperature difference, which is of interest to us. The teacher would usually have to pick out one of the students to help him with the experiment. This way the teacher will be able to run the experiment alone.