Math problem with Jennys newest tutorial?!!

[Swedish leo]

Hi

I am having trouble with the math in the disappering pinwheel.

Somehowe I get lost and do not get matching parts like Jenny do.

I attache some picture so you can see.

I figure it is a mathproblem. I do fine with whole and half inches but after that I am lost.

My pinnwheel is 12 whole inches and 1 half inches and 2 lines. in square.
How do I divied that in to thirds ?

How do you count the lines between the half and whole inches ? What are they called ?

I even tried to iron some creases to help me get the thirds but that did not work either.


Pleeeaassee Can you help me??

I realy would like to make this block

Thanks in advance

Annika, Confused Swede! ;-)