Open the rail, arrange balls and visualise numbers and arithmetic operations. Discover the number structure up to 20 and the concept of addition and subtraction by sliding balls. By representing numbers linear, in a rail, the development of a mental number line is stimulated. Make smart use of the colour change (red/white): in this way pupils easily recognise anchors like 5, 10, 15 or 20, without counting.-<B>Contents:</B><BR> wooden counting rail with 10 red and10 white balls (45 x 4.5 x 1.5)-