Here are my favourite easy ways to fill up five minutes with no preparation required.
Getting to know you warmers and fillers
1. True, true, lie. Students write some sentences about themselves. Some are true and some are lies. Then they mingle and can ask one another questions to find out which are lies.
2. CV interview. Draw up the basic structure of a CV on the board. Students in pairs interview each other to make each other's CV.
3. Guess the question. Write some words that are connected to you on the board (eg. your favourite sport, pet's name, age...). Make some easy and some harder. Explain that these are the answers to some questions about you. Students have to guess the questions. Students then do the same for themselves and guess the questions in small groups.
4. What am I like? Students write a few sentences about themselves on a piece of paper. (Tell them not to write about appearance or clothes as this will make it too easy.) Jumble up the papers and redistribute. Students then mingle and ask questions to find out who wrote their paper.
5. Same or different? Write up some sentence starters on the board. (Eg. My favourite place is... A colour that makes me feel good is... My favourite time of day is... I couldn't live without my... When I have free time I like to... I'm looking forward to...) Students complete for themselves and then compare in groups of 2-3. Encourage discussion. Each group feeds back to the class on something they have in common and something they disagree on.
Vocabulary and spelling warmers and fillers
6. Prefixes brainstorm. Put students into small teams. Each team must appoint one writer who will make the list. The team who can list the most correct examples in 2 minutes wins the game. Suggestions: pre-, int-, con-, dis-, mis-, un-, uni-, ob-, mono-, omni-...
7. Suffixes brainstorm. Procedure as above. Suggestions: -able, -ful, -ous, -tion, -sion, -ance, -ity, -ic, -ism, -ive...
8. Words with X number of letters brainstorm. For low levels, start with 4 or 5. Higher levels, more letters. Points are only awarded for correctly spelled words.
9. Rhymes brainstorm. Students in teams have 2 minutes to list words that rhyme with the word you give.
10. Categories brainstorm. This can be good if you split the class into two teams and they make their lists on the board. The team that can list the most in 2 minutes wins. Points are only awarded for correctly spelled words. Clothes, jobs, animals, foods, countries...
11. Shapes quiz. Draw some shapes on the board (circle, oval, triangle, square, rectangle, pentagon, hexagon, octagon...) and students in small groups write down their answers. Include some shapes they will know, and some you think they won't know.
12. Spelling race. Good for revising vocabulary from a previous lesson, or spellings that students persistently get wrong. Divide the class into two; one player from each team must write up the word you call out. First team with the correct spelling gets the point.
13. Back spelling. Arrange students in two lines facing the board and give a word to the two students at the back. They must tell the word to the person in front of them but are not allowed to say anything. Instead they must spell out the word by using their finger like a pencil on the next person's back. First team to accurately pass the word to the front of the line gets the point.
14. Word chain. Students are in two teams. Give a first word and students must continue with a word that starts with the last letter of that word (eg. cat-table-egg). This can be done on the board and the team with the longest chain after two minutes wins. Make it more difficult if the students can handle it by specifying a category. Alternatively, use a ball and play the game orally. A student from one team says the first word, then tosses the ball to a player on the other team who must give the next word. If a student can't think of a word or repeats one that has already been said, they are out of the game.
15. Geography quiz. Use any facts you know off the top of your head. (What is the capital city of... what is the currency of... which language is spoken in... what colours are on the flag of...)
16. Smartphone challenge. Challenge the learners to research specific items of vocabulary using their smartphones. For example, give a list of animals and learners must find the word for the baby animal (cat/kitten, horse/foal, bear/cub...), or a group of animals (sheep/flock, lion/pride, shoal/fish...). My students are usually excited to be allowed to use their phones in class for once. They can do this in groups and the first team to find all the words is the winner.
Grammar warmers and fillers
17. Verb forms revision. Students in small teams; each team has a small whiteboard, if available (paper if not). Call out a verb and students have to write the form that you specify (past simple, past participle...). The first team to write the correct form and hold up their whiteboard gets the point.
18. Present passive practice. Write up the structure "_____ is made from _____". Students in small groups have to make as many sentences as they can using that structure, but cannot use a word more than once. (Paper is made from wood, cheese is made from milk...) Set a time limit of about 3 minutes.
19. Grammar noughts and crosses. Draw a 3x3 grid on the board and write a word in each square. Students are in two teams. Decide which team goes first by coin toss or drawing straws. To take a square, the team must make a sentence with at least 10 words using the word in that square and the grammar structure you specify. If they cannot, it is the other team's turn.
Listening and pronunciation warmers and fillers
20. Minimal pairs race. Write up lots of minimal pairs in a random cloud on the board. For example ship/sheep, eyes/ice, my/might... Divide the class into two teams. Call out a word and one player from each team has to touch the word you said (or circle it with a pen if you prefer). The first to get the correct word wins a point.
21. Numbers race. Same as above but write up lots of numbers.
22. Shopping list memory game. Read out your shopping list with about 15 items. Students are not allowed to write while you talk. Then they make a list afterwards to see how many they can remember.
23. Running dictation. Divide students into pairs and stick a short reading text on the wall on the other side of the classroom. One student will be the runner and the other will be the writer.
24. Shouting dictation. If you don't have the space for a running dictation, have pairs standing or seated a few feet away from each other and one dictates to the other by shouting. Use different sections of text so that one student doesn't end up shouting for all the others.