A: Draw a 3x3 grid, with the boxes labeled 1 through 9 in the usual order (left to right; top to bottom).

B:For each of the following instructions you must write a number, greater than 10, starting in one box and going across (left to right) or down, with one digit to each box. Your answers should fill the grid, with no two answers overlapping.

C:Starting with a box whose number is a square, write a square number.

D:Starting with a box whose number is a cube, write a cube number.

E:Starting in a box whose number is prime, write a prime number whose digits add up to an even number.

F:Starting with a box whose number is even, write an even number

Unfortunately, one of the copies of my instructions had part F completely missing. Each child turned in a 3x3 grid which was correct for the version they had been given. By coincidence, they turned in identical grids.

How did they fill out their grids?

With only 3 numbers to fill the grid they have to all be 3 digit numbers.  They will also have to be oriented either all downward or all left and right.

They can't all go downward because 2 and 3 are only prime.

So there is one number either left from 1 or right from 3,
one number either left from 4 or right from 6, and
one number either left from 7 or right from 9.

You can't go right from 6, so you have to go left from 4 (the square)
You can no longer go right from 9, so you have to go left from 7 (the prime)
You have to go left from 1 (the cube)

Which numbers did they use?  I guess that's the coincidence.