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A wooden tray contains 4 boxes with lids:

1) 5 bars of each coloured bead bars 1-9;

2) 5 bars of each of the grey bead bars 1-9;

3) black and white bead stairs 1-9;

4) 23 golden bead bards of 10.

The purposes of this material:

1. Introduces the child to the unit combination of subtraction.

2. Teaches how to subtract concrete representation of negative functions.

3. Preparation for algebra (equal quantities of opposite sign eliminate each other).