You could just as well switch the "equality" and "fairness" signs in the great picture you showed. — Haglund

Notice that it's equality, not equity, in the image? Some versions of the image have "equity" in the place of "fairness". In the first image, the boxes are shared equally - each person has one. In the second the boxes are not shared equally, but there is equality.

I use this to show children why someone might need more attention or support than someone else.

It's a great image! Telling about everything about fairness, equality, equity (fairness?), sharing, etc. I don't even think the words are needed.

It's a great image! — Haglund

Yep. I've not been able to find out where it is from. It is widely used, making it hard to find the artist.

The middle child has the least problems...

What if the tall guy were a white boy and the small a black boy (but equal heights). If the white boy gets the jobs easier than the black boy, how should the boxes be interpreted to establish equity or fairness?