Draw a 2d graph, on the vertical axis put A-is-false at the bottom and A-is-true at the top. On the horizontal axis put B-is-false on the left and B-is-true on

Draw a 2d graph, on the vertical axis put A-is-false at the bottom and A-is-true at the top. On the horizontal axis put B-is-false on the left and B-is-true on the right. Now 'fill in' this graph with an X if the combination of A and B is True according to the XOR function, and a O otherwise. You'll find you get similar symbols in opposite corners and can't separate the two groups of symbols by drawing a single straight line. Now try the same for OR, NOT, AND, NOR and NAND.