Abstract: A test specimen includes four sensed elements and six connection elements for connecting the sensed elements, the sensed elements being releasably connectable by the connection elements in such a way that each sensed element touches precisely three connection elements at the end faces thereof and that the sensed elements and the connection elements in their entirety form a tetrahedron on the corners of which the sensed elements are arranged. The material and/or the dimensions of the sensed elements and the material and/or the dimensions of the connection elements are adapted to one another in such a way that, under standard measurement conditions, the total coefficient of linear expansion from one sensed point to the next sensed point on different sensed elements is essentially zero.