Detailed instructions for working a group puzzle of type 'Thorndike'

This is a signature puzzle named 'Thorndike'

The 9 elements in each group of this type of puzzle are: T, H, O, R, N, D, I, K, and E.

Every group in the puzzle must contain exactly this set of elements.

Each row is a group numbered as shown in this Thorndike figure.

In a Thorndike puzzle, each row is a group numbered as shown in the figure above.

Each column is a group numbered as shown in this Thorndike figure.

In a Thorndike puzzle, each column is a group numbered as shown in the figure above.

Each 3x3 square is a group numbered as shown in this Thorndike figure.

In a Thorndike puzzle, each 3x3 square is a group numbered as shown in the figure above.