Abstract: An educational apparatus has a controller linked with student devices, and a teacher device. Each student device is in the form of a desk with a board, a touch sensor array in the board, a display physically separate from the array, and permanent indicia. The apparatus recognises touch by a student on the board, and this is mapped to content of an overlay sheet of paper placed on the board. Moreover, multiple devices may be juxtaposed, and events may be recognised based on all of the group of devices together. An example is a paper sheet covering four devices together and having a map printed on it, in which the software recognised a particular location of touch on a particular device as being a specific region on the map.

Abstract: The invention relates to method for the stepwise removal of bacteria from a fermentation broth. According to said method, the bacteria in the fermentation broth are mixed with a retention promoter mixture in a first process step and the pretreated bacteria are removed by precoat filtration in a second process step. The inventive method uses a retention promoter mixture from bentonite and polycations such as PEI or polyDADMAC and is suitable for treating large quantities of bacteria. The filter cake obtained with bentonite/PEI has a substantially improved quality.