1. LEA 3D-puzzle

Measurement of visual acuity with symbols requires the concept "similar/same" which develops at the age of 14-20 months . Since the concept of "similar" develops earlier in matching colours, the colourful side of the LEA 3D-puzzle is used first. This child has also names for the symbols, recognises the orientation of the puzzle pieces with ease and turns them with well co-ordinated hand movements.

"Let's place all the puzzle pieces on the table. Then you can put them back."
"Where would you put this? THERE."
"This goes here.. and this is box."
"Then we turn the puzzle.. where would you put this piece?"

When the puzzle is turned we see that she can also match black and white forms. Like many other children she turns the colourful side up when placing the puzzle pieces in the cut-outs.