Flying on pedal power: compound adjectives like 70-pound and human-powered

Q: What are compound adjectives?

A compound adjective is two or three words acting as one adjective , usually joined by hyphens before a noun: a 70-pound plane , a human-powered aircraft , a record-breaking flight . It saves a longer phrase: a plane that weighed 70 pounds . The B2 lesson Flying on pedal power on edio.ai teaches compound adjectives through the Gossamer Condor, the pedal-powered plane that won the Kremer Prize in 1977.

Q: What are some examples of compound adjectives?

Four from Flying on pedal power on edio.ai: The Gossamer Condor was a 70-pound plane with a 96-foot wingspan. The human-powered plane flew a one-mile figure eight. In 1979, the Albatross made a 22.5-mile trip across the English Channel. Adela thinks solar-powered planes are the future. A number, a noun or an adverb can come first , as in well-known .

Q: What's the difference between -ed and -ing compound adjectives?

It depends on who does the action . If the noun does it, use -ing : a flight that breaks a record is a record-breaking flight . If something does it to the noun, use the past participle: a plane that a human powers is a human-powered plane . So a record-broken flight and a human-power plane are both wrong. A table in the grammar chapter of Flying on pedal power on edio.ai sorts eight of them.

Q: Is it “a three-weeks trip” or “a three-week trip”?

It's a three-week trip : in front of a noun, the number compound stays singular . The same rule gives a 70-pound plane , a ten-minute video and a 50-year-old bike . Outside the compound, the plural returns without hyphens: The trip took three weeks. The student is 21 years old. Every wrong reply in the chat of Flying on pedal power on edio.ai hides a slip like this, an extra 's or a wrong participle.

Q: What was the Gossamer Condor?

It was a human-powered airplane designed by Paul MacCready's team at AeroVironment, a California company. It weighed about 70 pounds empty and had a 96-foot wingspan, and the pilot's pedals turned a bicycle chain, which turned the propeller. On August 23, 1977, at Shafter, California, the bicycle racer Bryan Allen flew it around the prize course at about 10 miles per hour. Isaiah's explainer in Flying on pedal power on edio.ai tells the story.

Q: What was the Kremer Prize?

It was a prize for human-powered flight , offered in 1959 by the British industrialist Henry Kremer, with rules set by the Royal Aeronautical Society: fly a figure eight around two pylons half a mile apart. For 18 years, nobody won, because earlier planes were too heavy and couldn't turn well. In 1977 the Condor became the first to win it, and the team took 50,000 pounds in British money. Flying on pedal power on edio.ai explains how.

Q: How do I teach compound adjectives to B2 students?

Start from the long phrase, then compress it : a plane that weighed 70 pounds → a 70-pound plane . Do number compounds first, since the missing -s is the main trap, then add -ed and -ing compounds with the question “Who does the action?” Flying on pedal power on edio.ai moves from Isaiah's explainer and an office argument to the scheme, four drills and a pitch for an expedition.

Q: What's a good game for practicing compound adjectives?

Try “Say it in one word” : one team reads out a long description, such as a bike that is 50 years old or a car that a battery powers , and the other team has ten seconds to answer with a compound: a 50-year-old bike , a battery-powered car . For speaking, the boxes in Flying on pedal power on edio.ai have students pitch their own zero-emission expedition.

Q: What's good homework for compound adjectives?

Good homework moves the same idea before and after the noun : The tour lasts three hours. → It's a ___ tour. Add a quiz on meaning ( a two-hour flight is one flight that lasts two hours) and a short text with gaps. All ten homework tasks in Flying on pedal power on edio.ai check themselves, ending with Charlene's pitch and Harper's answer to Adela.

This B2 ESL lesson plan teaches compound adjectives through the Gossamer Condor, the 70-pound plane that won the Kremer Prize for human-powered flight in 1977.

Grammar: Number + singular noun before a noun (a 96-foot wingspan, not 96-feet), a past participle for a passive meaning (human-powered, well-known), -ing for an active one (record-breaking) and the hyphens.
Topic: How a huge, light plane won a prize nobody had won for 18 years, with words like wingspan, pylon, emissions and stamina.
Activities: An explainer, an office argument and a reader's voice memo, self-checking drills, a chat and a pitch for a zero-emission expedition.

What's inside

Chapter 1Warm-up: pedal power
- PictureUnlock
- Spin the wheel and answerSpin the wheelUnlock
- Study the words: flying on human powerVocabularyTry it
- Look at the pictures and choose the wordChoose by pictureUnlock
Chapter 2Eighteen years, one figure eight
- Look at the photo: a plane you pedalPictureUnlock
- Read Isaiah's explainer on The Why DeskArticleUnlock
- Read and mark true or falseTrue or falseUnlock
- Read again and choose the correct answerQuizUnlock
- Match the paragraphs and the headingsMatchUnlock
Chapter 3How far can your legs take you?
- Listen to Isaiah and HarperListeningTry it
- Transcript, for the teacherUnlock
- Listen and choose the correct answerQuizUnlock
- Listen to the Reader's Rebuttal: Adela's voice memoListeningUnlock
- Transcript, for the teacherUnlock
- Listen and mark true or falseTrue or falseUnlock
Chapter 4Grammar: a 70-pound plane
- Study the scheme: a 70-pound planeGrammar schemeTry it
- Choose the correct optionChoose the optionUnlock
- Fill in the gaps: make one adjective from the words in bracketsFill in the gapsTry it
- Fill in the table: active or passive? Then make the adjectiveFill in the tableUnlock
- Choose the correct answer: which sentence is correct?QuizUnlock
Chapter 5Let's talk: pitch a zero-emission expedition
- Choose the right replies: pitch an expedition to HarperChatTry it
- Put the parts of Harper's pitch in the correct orderDrag and dropUnlock
- Choose the correct option: a pitch templateChoose the optionUnlock
- Open a box and pitch your expeditionOpen the boxUnlock
Chapter 6Homework
- Match the words and the meaningsMatchUnlock
- Unscramble the wordsAnagramUnlock
- Fill in the gaps with the lesson's wordsFill in the gapsUnlock
- Find the matching pairs: words and meaningsMemory gameUnlock
- Choose the correct option: new sentencesChoose the optionUnlock
- Fill in the gaps: before the noun or after itFill in the gapsUnlock
- Put the words in the correct orderUnjumbleUnlock
- Choose the correct answer: what does it mean?QuizUnlock
- Drag the words into the gaps: Charlene's pitchDrag and dropUnlock
- Choose the correct option: Harper answers AdelaChoose the optionUnlock

Vocabulary

12 words and phrases from the lesson, each with a picture and audio in edio.

+9 more with pictures and audio in the lessonMore words

figure eight
pylon
aircraft
lever
lightweight
documentary
expedition
emissions
stamina

Grammar: compound adjectives with numbers and participles

A compound adjective packs a phrase into one hyphenated word before a noun: a plane that weighed 70 pounds becomes a 70-pound plane. A prize-winning plane with a 96-foot wingspan and pedals for an engine needs plenty of them, so learners drop the plural -s inside the compound, choose -ed or -ing and place the hyphens.

A 70-pound plane, a record-breaking flight

A compound adjective is two or three words joined with hyphens. Before a noun, it works like one adjective.

Number + noun: a 70-pound plane

A number and a noun joined by a hyphen work as one adjective: a 70-pound plane, a 96-foot wingspan, a two-day ride. Adjectives have no plural, so the noun stays singular: not a 70-pounds plane. After the noun, the plural returns: The plane weighed 70 pounds.

Number + noun: one adjective, no -s

Before a noun	The same idea in a sentence
a 70-pound plane	The plane weighed 70 pounds.
a 96-foot wingspan	The wings measured 96 feet from tip to tip.
a 21-year-old student	The student is 21 years old.
a two-day ride	The ride takes two days.
a 20-mile route	The route is 20 miles long.
a 27-minute film	The film lasts 27 minutes.

No -s before the noun

A number compound is an adjective, and English adjectives have no plural: a three-week trip, a 70-pound plane (not: a three-weeks trip, a 70-pounds plane). In other places in the sentence, the plural comes back, with no hyphens: The trip took three weeks. The student is 21 years old.

Passive meaning: human-powered, well-known

Use a past participle when something is done to the noun: a human-powered plane is powered by a human, and a hand-built canoe was built by hand. Well + past participle follows the same logic: a well-known pilot, a well-designed wing, a well-trained racer.

Pattern	Examples	Meaning
noun + past participle	a human-powered plane, a solar-powered boat, a hand-built canoe	passive meaning: it is powered by a human or by the sun; it was built by hand
well + past participle	a well-known pilot, a well-designed wing, a well-trained racer	passive meaning: many people know her; someone designed it well
noun + -ing	a record-breaking flight, an energy-saving design	active meaning: it breaks a record; it saves energy
long / slow / hard + -ing	a long-lasting battery, a slow-moving plane, a hard-working team	active meaning: it lasts a long time; it moves slowly; they work hard

Active meaning: record-breaking, long-lasting

Use -ing when the noun does the action itself: a flight that breaks a record is a record-breaking flight, and a battery that lasts a long time is long-lasting. Ask who does the action whenever -ed and -ing both seem possible.

-ed or -ing?

Ask who does the action. The noun does it → -ing (active): a flight that breaks a record = a record-breaking flight. Something or someone does it to the noun → past participle (passive): a plane powered by a human = a human-powered plane. Not: a record-broken flight, a human-power plane.

Hyphens before a noun and after be

Before a noun, hyphens join every part: a well-known pilot, a 21-year-old student, with two hyphens and no -s. After be, well compounds usually lose the hyphen: The pilot is well known. Many others keep it: The flight was record-breaking.

Hyphens

Hyphens join the words before a noun: a well-known pilot, a 21-year-old student (two hyphens). After be, people usually write well + participle without a hyphen: The pilot is well known. Many others keep it: The plane was human-powered. The flight was record-breaking.

Common mistakes

Four slips: a 70-pounds plane and a three-weeks trip keep a plural; a human-power plane loses the participle; a record-broken flight uses a passive form for an active idea. Outside the compound, the plural comes back: The trip took three weeks.

It was a 70-pounds plane.
It was a 70-pound plane.
no -s before the noun
We planned a three-weeks trip.
We planned a three-week trip.
no -s before the noun
Allen flew a human-power plane.
Allen flew a human-powered plane.
a human powers it: passive, past participle
It was a record-broken flight.
It was a record-breaking flight.
the flight breaks a record: active, -ing

At The Why Desk

The Gossamer Condor was a 70-pound plane with a 96-foot wingspan.
In 1979, the Albatross made a 22.5-mile trip across the English Channel.
The human-powered plane flew a one-mile figure eight.
Harper wants a two-day ride on a pedal-powered boat.
A 27-minute film about the flight won an Oscar.
Adela thinks solar-powered planes are the future.

More lessons on this grammar: Word formation lessons and exercises · Adjectives and adverbs lessons and exercises

Try the compound adjectives exercises

Try them yourself: these are the same exercises your students do in edio.

What's in the lesson

20 auto-checked exercises
5 games
1 article
1 grammar scheme
1 set of word cards
2 audio clips
2 pictures
2 transcripts

The main objectives of this lesson are to:

put a number and a singular noun before a noun: The Gossamer Condor was a 70-pound plane with a 96-foot wingspan.
keep the plural outside the compound: a three-week trip, but The trip took three weeks.
choose a past participle or -ing by asking who does the action: a human-powered plane, a record-breaking flight
write the hyphens before a noun: a well-known pilot, a 21-year-old student
pitch a zero-emission expedition: It's a 45-mile route, so about 15 miles a day.

Lesson 31 is the third lesson of Exploring the extremes, unit 8 of English B2.1 · How the World Works. Lesson 29 gave sizes after the noun (18 inches long); here numbers move in front of it as one adjective. The participles echo the passive of unit 2, and the word building continues lesson 26. Lesson 32, the course's last, turns to only, even and just. A prize-winning plane described by its weight, wingspan and power source is a natural showcase for compound adjectives.

Students spin a wheel about bikes, records and human power, then learn twelve words, from wingspan and pylon to emissions and stamina, with pictures and audio. They read Isaiah's explainer on the Condor and the Kremer Prize, then hear Harper pitch a pedal-powered boat trip while Isaiah argues the numbers, and Adela, an engineering student, make the case for solar power; both are AI-voiced. The grammar chapter has the scheme and four self-checking exercises, among them a table that sorts active and passive compounds. The speaking chapter builds a pitch step by step: a chat with Harper, her own pitch to put in order, a template with gaps and boxes for pitching in class.

All ten homework tasks check themselves: a word match, an anagram, gaps with the flight words and a memory game, then compounds to choose in new sentences, gaps before or after the noun, word order, a quiz on what each compound means, Charlene's bike-expedition pitch and Harper's answer to Adela.

Grammar:: compound adjectives · compound adjectives with numbers · compound adjectives with participles · hyphens
Topic:: the Gossamer Condor · Paul MacCready · Bryan Allen · the Kremer Prize · human-powered flight · Shafter, California · The Why Desk

Teaching tips

Squeeze long phrases into one word: write a plane that weighs 70 pounds and a flight that breaks a record on the board, and have students turn each into a compound before the noun.
Say the plural out loud, then remove it: The ride takes two days becomes a two-day ride. Students hear the -s disappear and repeat with weeks, miles and years.
Play the office argument twice: first to note each side's view of human power, then to list every compound, from slow-moving to long-lasting. Students then decide whether Isaiah's numbers help Harper.
Let pairs pitch their own expedition after the template: the idea, the route, the team, why it matters and the result, each with one compound such as a three-day canoe trip or a 45-mile route.

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The whole course: English B2.1 · How the World Works

32 lessons for adults at B2 in American English, each answering one question about how the world works. The team of The Why Desk, a small online magazine in Pittsburgh, takes on one question a week, from the day a computer beat the world chess champion to eight people sealed inside Biosphere 2. Learners tell stories with narrative tenses, speculate about the past and the future, and report what experts claim. The practice exercises check themselves.See the course

Unit 1 AI and the future of work
narrative tenses, by and until, be bound to and be likely to, the future perfect
Unit 2 Health breakthroughs
the third conditional, the past perfect and past continuous passive, have something done, the passive with two objects
Unit 3 Moving people
the past perfect continuous, the passive infinitive and -ing form, it's worth and there's no point, the future in the past
Unit 4 Wildlife comebacks
reporting verbs with a that clause, with an object and infinitive and with -ing, verbs of perception
Unit 5 Pop culture goes global
comment adverbs, wish and if only for the present and the past, have someone do and get someone to do
Unit 6 Money and smart choices
-ever words and no matter, should have and could have, prepositions for numbers and change, it's time and would rather
Unit 7 Language and communication
must have, might have and can't have, verb prefixes and suffixes, past modals in continuous and passive forms, agreement with quantities
Unit 8 Exploring the extremes
dimension nouns, the future continuous and future perfect continuous, compound adjectives, only, even and just
1. Lesson 29A walk on the ocean floorDimension nouns and phrases: depth, width, height
2. Lesson 30Six months of night at the South PoleThe future continuous and the future perfect continuous
3. Lesson 31 · you're hereFlying on pedal powerCompound adjectives with numbers and participles
4. Lesson 32Two years under glassFocus adverbs: only, even, just and at all

Questions about this lesson

What are compound adjectives?

A compound adjective is two or three words acting as one adjective, usually joined by hyphens before a noun: a 70-pound plane, a human-powered aircraft, a record-breaking flight. It saves a longer phrase: a plane that weighed 70 pounds. The B2 lesson Flying on pedal power on edio.ai teaches compound adjectives through the Gossamer Condor, the pedal-powered plane that won the Kremer Prize in 1977.

How do you form compound adjectives with numbers?

Join the number and a singular noun with a hyphen, and put them before the noun: a 96-foot wingspan, a two-day ride, a 27-minute film. There's no plural -s, because adjectives don't take one: a three-week trip, not a three-weeks trip. Ages take two hyphens: a 21-year-old student. The scheme in Flying on pedal power on edio.ai pairs each compound with the same idea in a full sentence.

What are some examples of compound adjectives?

Four from Flying on pedal power on edio.ai: The Gossamer Condor was a 70-pound plane with a 96-foot wingspan. The human-powered plane flew a one-mile figure eight. In 1979, the Albatross made a 22.5-mile trip across the English Channel. Adela thinks solar-powered planes are the future. A number, a noun or an adverb can come first, as in well-known.

What's the difference between -ed and -ing compound adjectives?

It depends on who does the action. If the noun does it, use -ing: a flight that breaks a record is a record-breaking flight. If something does it to the noun, use the past participle: a plane that a human powers is a human-powered plane. So a record-broken flight and a human-power plane are both wrong. A table in the grammar chapter of Flying on pedal power on edio.ai sorts eight of them.

Is it “a three-weeks trip” or “a three-week trip”?

It's a three-week trip: in front of a noun, the number compound stays singular. The same rule gives a 70-pound plane, a ten-minute video and a 50-year-old bike. Outside the compound, the plural returns without hyphens: The trip took three weeks. The student is 21 years old. Every wrong reply in the chat of Flying on pedal power on edio.ai hides a slip like this, an extra 's or a wrong participle.

What was the Gossamer Condor?

It was a human-powered airplane designed by Paul MacCready's team at AeroVironment, a California company. It weighed about 70 pounds empty and had a 96-foot wingspan, and the pilot's pedals turned a bicycle chain, which turned the propeller. On August 23, 1977, at Shafter, California, the bicycle racer Bryan Allen flew it around the prize course at about 10 miles per hour. Isaiah's explainer in Flying on pedal power on edio.ai tells the story.

What was the Kremer Prize?

It was a prize for human-powered flight, offered in 1959 by the British industrialist Henry Kremer, with rules set by the Royal Aeronautical Society: fly a figure eight around two pylons half a mile apart. For 18 years, nobody won, because earlier planes were too heavy and couldn't turn well. In 1977 the Condor became the first to win it, and the team took 50,000 pounds in British money. Flying on pedal power on edio.ai explains how.

How do I teach compound adjectives to B2 students?

Start from the long phrase, then compress it: a plane that weighed 70 pounds → a 70-pound plane. Do number compounds first, since the missing -s is the main trap, then add -ed and -ing compounds with the question “Who does the action?” Flying on pedal power on edio.ai moves from Isaiah's explainer and an office argument to the scheme, four drills and a pitch for an expedition.

What's a good game for practicing compound adjectives?

Try “Say it in one word”: one team reads out a long description, such as a bike that is 50 years old or a car that a battery powers, and the other team has ten seconds to answer with a compound: a 50-year-old bike, a battery-powered car. For speaking, the boxes in Flying on pedal power on edio.ai have students pitch their own zero-emission expedition.

What's good homework for compound adjectives?

Good homework moves the same idea before and after the noun: The tour lasts three hours. → It's a ___ tour. Add a quiz on meaning (a two-hour flight is one flight that lasts two hours) and a short text with gaps. All ten homework tasks in Flying on pedal power on edio.ai check themselves, ending with Charlene's pitch and Harper's answer to Adela.

How do you practice compound adjectives one-to-one?

Plan a trip together: the teacher asks How long is the route? and What kind of trip is it?, and the student answers with compounds such as a 45-mile route and a human-powered trip, then asks the teacher about a trip of their own. The chat in Flying on pedal power on edio.ai works without a partner: Harper helps the student pitch a three-day canoe trip.

Are there interactive exercises for compound adjectives?

Yes. This page plays three parts of Flying on pedal power, a B2 lesson on edio.ai, with no account: Harper's pitch for a pedal-boat trip as Isaiah argues the numbers, a gap-fill that joins words into one adjective and a chat that pitches a canoe trip to Harper. Everything else needs an account.

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About this lesson

What's inside

Vocabulary

Grammar: compound adjectives with numbers and participles

Number + noun: a 70-pound plane

Number + noun: one adjective, no -s

Passive meaning: human-powered, well-known

Active meaning: record-breaking, long-lasting

Hyphens before a noun and after be

Common mistakes

At The Why Desk

Try the compound adjectives exercises

What's in the lesson

The main objectives of this lesson are to:

Teaching tips

Teach the whole lesson in edio

Start a free trial

Open the lesson

Teach it live or as homework

The whole course: English B2.1 · How the World Works

Unit 1 AI and the future of work

Unit 2 Health breakthroughs

Unit 3 Moving people

Unit 4 Wildlife comebacks

Unit 5 Pop culture goes global

Unit 6 Money and smart choices

Unit 7 Language and communication

Unit 8 Exploring the extremes

Questions about this lesson

Teach this lesson with your students