Abstract: A system and method is provided that enables children to learn and practice number sense and basic numerical operations. In one embodiment, children are invited to move objects that represent units, as well as objects that represent tens, in order to visualize the process of solving basic numerical operations. The movements that are allowed are subject to restrictions and other special behavior, which help children to gain insight in the numerical processes of these basic numerical operations in such a way that a solid foundation is created that prepares them to solve these operations on a purely formal level in a later stage.

Abstract: The invention relates to a power amplifier module comprising a first amplifier 2 having a first front-end 4 and a first backend amplifier stage 5 and a second amplifier 3 having a second front-end 6 and a second backend amplifier stage 7, the first amplifier and the second amplifier being arranged in a Bridge Tied Load (BTL) configuration with feedback over the load, characterized in that the first and the second backend amplifier stages having point symmetrical transfer functions with respect to the origin, the input current i1 of the first backend amplifier stage being substantially equal to the input current i2 of the second backend amplifier stage.