Who it's for

Secondary and high school English, ESL and adult-education classes. WordCracker's Terms ask players to be at least 13, so it is meant for classes of 13 and older.

The rules your class needs

Teams take turns adding one letter anywhere in the string: front, end or middle.
The letters must always sit inside some real English word.
A team that completes a word of four or more letters loses the round. Short words (CAT, THE) don't count.
If you think the other team is bluffing, challenge. They must name a word containing the letters. If they can, the challengers lose the round; if they can't, the bluffers do.

Setting it up (five minutes, once)

Open wordcracker.net on the computer you project from, before class. The first visit runs a short interactive tutorial; finish it so it doesn't play in front of the room.
For a team game, open Duel → Pass & Play. The two "players" are your two teams. The default match, best of 3 with no timer, suits a lesson.
For the whole class against the computer, open Solo → Quick Match and pick Easy. The class votes on each letter.
Letters are dragged into place: with a finger on a touchscreen board, or with the mouse.

A round, step by step

Team A plays E. Team B adds A: EA.
Team A adds R at the end: EAR. Three letters, so it's safe.
Team B sees the danger: EARN, EARL, BEAR, FEAR, NEAR are all words. They try an R in front: REAR. That's a four-letter word, so Team A challenges and Team B loses the round.
What could Team B have done? EART (inside HEART and EARTH) keeps going without finishing anything.

What it practises

Spelling patterns. To survive, students have to know which letter clusters can occur inside words (EART, OUGH, TION) and which can't.
Prefixes and suffixes. Letters can go in front and behind, so teams think about RE-, UN-, -ING and -NESS as ways out of a tight spot.
Vocabulary. A team that defends a challenge with an unfamiliar word gives you a natural moment to talk about it. The Dictionary in the game's More menu looks words up.
Reasoning under uncertainty. Deciding when to challenge is a judgement call about what the other team probably knows.

Variations

Warm-up: one round on the board while students settle, five minutes or less.
Defend-a-word: a team that answers a bluff challenge must also give a sentence using their word.
Paper version: the same rules work on a whiteboard. Use the online game when you want a neutral referee.

Questions

Do students need accounts or devices?

No. One device run by the teacher is enough. Nothing has to be installed.

Is the word list classroom-safe?

The word list is a standard English word-game dictionary with slurs and explicit terms removed. The computer opponent never plays crude words, but as in any full dictionary, some vulgar words exist and are accepted if a player types one.

Does it cost anything?

No. The full game is free.

OPEN THE GAME