STEINBERG: Well, we could put PUZZLE PIECE in the third row, but then we’ll have a bunch of three-letter words clogging up the grid.

Image Credit... Natan Last

LAST: Right! This is where we’re trying to set up our next pair of constructors — the ones who will complete the filling of the puzzle — for success. There are way fewer three-letter words than four-letter words, which means our colleagues won’t have a great choice of fill, so let’s go with one of our other themers.

STEINBERG: Before we do that, though, let’s back up a little. One longstanding rule is that grids must be rotationally symmetric, which means that they look the same if you turn them upside-down (other kinds of symmetry exist, too, but that’s a topic for an advanced grid-design column!). Maintaining rotational symmetry can be a pain, but fortunately, CrossFire takes care of that for you. All you do to add a symmetrical pair of blocks is press the period key in one of the two squares (or in the exact center, if we’re being precise). And the software places the numbers in the grid for you, which is really convenient.

LAST: Yup! And those symmetry rules mean theme entries must be arranged symmetrically. So once we lock in MACBOOK AIR, we have to stick a theme entry with the same number of letters in the opposite, lower-right slot. CALL NUMBER is our only other 10-letter option, so in it goes.

STEINBERG: Remember that we also we want plenty of space between theme answers … with all of that in mind, how’s this?

Image Credit... Natan Last

Those Pesky Letters

LAST: A thing of beauty! Now is a good time to talk about how we can use black squares, and a knowledge of which letters appear in more words in English, to construct a grid that’s easy to fill. In fact, without knowing it, we’ve already helped out the next set of constructors: The harder letters (think high Scrabble scores, like J, Q or Z) in our theme answers are tucked away, which means we can deal with them more easily — it would be much more constraining if both Z’s of PUZZLE PIECE were in the middle of the grid, where they would interact more with other theme entries.