There are 3 two-letter words that can be made by unscrambling the letters in kai. No common everyday answer stands out among these two-letter results, so let the score decide: the highest-scoring words are ka and ki, each worth 6 points in Scrabble.
The full list follows, sorted A to Z; every score reflects tile constraints and skips board bonuses.
The highest-scoring plays from these letters are ka and ki, worth 6 points in Scrabble, and nothing else built from kai earns more points in Scrabble. Words With Friends prices the same letters differently, so the top of the list changes on a Words With Friends board. Both scores count tile values only and exclude premium squares.
The letters in kai produce 3 valid words in the Scrabble and Words With Friends dictionaries. The word count by length is: 3 two-letter words.
The anagram solver inside UnscrambleX compares kai against the dictionaries used by Scrabble, Words With Friends, Word Jumble, and Text Twist, keeps every arrangement those dictionaries contain, and sorts the confirmed words by tile score. That sorting step is why ka and ki appear at the top of the results. A word on this page is a legal play in Scrabble and Words With Friends, not a letter combination that only looks like a word.
Unscrambling kai produces two kinds of plays in Scrabble and Words With Friends: one high-scoring word, and one short word that fits a crowded board.
The high-scoring play is ka. The short plays are ai and ka, and they cover the turns when the board leaves no open line long enough for the bigger word.
The score gap is exact: the lowest-scoring word from these letters earns 2 points in Scrabble and the highest-scoring word earns 6 points. The letters are identical in both cases, so the board decides the value of the turn.
UnscrambleX lists every word from these letters with its Scrabble score and its Words With Friends score, so the choice between points and board position is made from numbers instead of memory.
The results list works as a vocabulary drill for Scrabble and Words With Friends players. Cover the list, rearrange kai in your head, and count how many of the 3 words you find before you check the answers.
Experienced players find the long words such as ka and ki without help. The short words are the ones that go unnoticed, and short words decide close games in Scrabble, Words With Friends, and Text Twist.
Repeat the drill on a few letter sets each day. Vowel positions, common endings such as -ed and -ing, and high-value tiles become recognisable without an unscrambler.
Unscrambling adds words that reading never supplies. No Scrabble player opens a dictionary to look for ai, and the word enters a playable vocabulary only because a results list produced it.
Spelling accuracy improves at the same time. Building ka from loose tiles forces one letter order and returns a correct or incorrect verdict inside the same move, which is faster feedback than a spelling test. Plays from kai range from 2 to 6 points in Scrabble, so every turn also asks a scoring question: take the points now, or keep the flexible tiles for the next turn.
Words assembled from tiles are remembered better than words only read, and timed games such as Text Twist and Word Jumble reward that recall directly.