What you'll need: A blackboard; that's it!
I recommend this version for junior highschool third years and older, but it may also work for work for JHS second years and highschoolers with a few tweaks. This is quite a heavily adapted version of Boggle, but if you think your students can handle the original version, the "real" rules are here:
https://www.ultraboardgames.com/boggle/game-rules.php
Explanation:
1. (Optional) Arrange the class into groups. I usually use pairs, but individually or groups of up to 5 will also work.
2. Write 16 letters on the blackboard in a 4x4 cube.
3. Each pair has 5 minute to search for words that can be constructed from the letters of sequentially adjacent letters, horizontally, vertically or diagonally. In the original game, words must be at least three letters long with no proper nouns etc., but to make it more accessible I allow 2 letter words, abbreviations and proper nouns, but you may want to stick to 3 letter words or above for highschoolers. Each pair uses a notebook or scrap piece of paper to write their list of words. Encourage your JTE to play as well!
4. (Optional) If you have time, play the game yourself before class, and write a list of hints on the board to help students who are struggling (eg. Find: a colour, a country, a job etc.) With higher level students you can also encourage them to look for prefixes and suffixes they can add like -ed, re- or plural s to make their work longer (for example, plant can become planted or even replanted!)
5. When the timer is up, ask students to raise their hand and say their best word. I usually start by asking for 5-letter words, then go down the list. Use your normal methods that you use to get students to answer questions.
6. Next is scoring! I usually ask students to count each letter in all the words they wrote down and take the first digit as their toal score (so 12 letters is 1 point, 56 letters is 5 points etc). This is usually just to get students thinking and more confident with their knowledge of vocabulary, so I don't typically penalise spelling, but you may wish students to check and score their classmates' lists to ensure only correctly spelled words are scored.
TIP: You can write 16 random letters if you want, but I tend to choose the boards with the most poissible words from an algorithm to give the students the best chance to find lots of words. You could also try to make one that deliberately includes some recent vocabulary for a vocabulary review.
The top four combinations are:
S E T S
P I R D
L A N E
S E T S
S D E S
T R N T
E I A E
S L P S
S P L S
E A I E
R T N R
O S E D
S R E S
O T A P
E N I L
S D E S
Happy hunting!