The secret race to build a weapon that would change the world forever.
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Ten words you'll meet in the story, unlocked four different ways. Do the thinking first, then reveal to check — the answer stays hidden until you press the button.
Each sentence gives you enough to guess the bold word. Say what you think it means, then reveal.
Read each definition and say the word before you reveal it.
Decide how the two words relate, then reveal.
Finish the common phrase, then reveal the missing word and why it pairs.
Read each part. After it, there's a quick comprehension check (try the questions from memory first), then one thing to discuss.
The story begins not with an explosion but with a letter. In the 1930s, physicists in Europe discovered that the atom could be split — and that splitting it might unleash a vast, sudden release of energy. Many of the brightest minds working on this were refugees who had fled fascism in Germany and Italy, and they were haunted by one thought: if such a weapon could be built, Nazi Germany might build it first.
In 1939, urged on by fellow scientists, Albert Einstein signed a letter to the American president, Franklin Roosevelt, warning that "extremely powerful bombs of a new type" might now be possible. The warning was taken seriously. Slowly at first, and then with enormous urgency after the United States entered the war in 1941, a secret programme was set up. It would come to be known, from its early offices in New York, as the Manhattan Project.
It was placed under the command of an army engineer, General Leslie Groves, who chose a brilliant, complicated physicist named J. Robert Oppenheimer to lead the scientific work. Their task was almost unimaginable: to turn a few lines in a physics paper into a working weapon, before the enemy could — and to tell almost no one they were doing it.
1. Why did so many of the scientists fear that Germany might build the bomb first?
2. What was the Einstein letter, and what did it lead to?
1. Splitting the atom had been discovered in Europe, and many of the leading physicists were refugees from fascism who knew how advanced German science was; they feared the Nazis would get there first.
2. A 1939 letter signed by Einstein warning President Roosevelt that powerful new bombs might be possible; it led to the secret programme that became the Manhattan Project.
What followed was one of the largest and most secretive efforts ever attempted. Whole towns were built where none had stood before. At Los Alamos, high in the New Mexico desert, thousands of scientists and their families were gathered behind fences to work on the bomb's design. At Oak Ridge in Tennessee and Hanford in Washington, vast plants were constructed to produce the rare materials — uranium and plutonium — that the weapon needed. More than a hundred thousand people were employed, yet the work was so tightly classified that most of them never knew what they were making.
The physics was as hard as the secrecy. To make the bomb work, a chain reaction had to be started and controlled with terrifying precision. Rival designs were argued over, tested and rebuilt. Money was spent on a scale that only a wartime government could command. And all the while, a quieter unease grew among some of the scientists: what exactly were they about to give the world?
Before dawn on 16 July 1945, in the desert at a site codenamed "Trinity", the first atomic device was detonated. The blast lit the sky brighter than the sun and was felt for miles. Watching it, Oppenheimer later recalled a line from an ancient Hindu text: "Now I am become Death, the destroyer of worlds." The weapon worked. By then, Germany had already surrendered — but the war in the Pacific went on.
1. Why were whole new towns like Los Alamos and Oak Ridge built, and why did most workers not know their real purpose?
2. What was the Trinity test, and what had changed in the war by the time it happened?
1. They were secret sites to design the bomb and to produce uranium and plutonium; the work was so classified that most of the workforce were told only their small part, not the whole purpose.
2. Trinity was the first atomic test, in the New Mexico desert on 16 July 1945; by then Germany had surrendered, but the war against Japan continued.
In early August 1945, the decision was taken to use the new weapon against Japan. On 6 August, an atomic bomb was dropped on the city of Hiroshima; three days later, a second was dropped on Nagasaki. Tens of thousands of people were killed at once, and many thousands more died afterwards from their injuries and from the effects of radiation. Most of the dead were civilians. On 15 August, Japan surrendered, and the Second World War came to an end.
The debate over that decision has never truly ended. To some, the bombings brought a swift close to a terrible war and spared the still greater loss of life that a full invasion of Japan might have caused. To others, the deliberate destruction of two cities full of civilians can never be justified. Both arguments are still made, seriously and in good faith, to this day.
For the scientists, the reckoning was personal. Oppenheimer, who had led the work, later spoke of the "sin" that physicists had come to know, and pressed for the new weapons to be controlled rather than multiplied. He was largely ignored. Within a few years the Soviet Union had built its own bomb, and the world entered the long, tense standoff of the nuclear age — a shadow under which, in a sense, we all still live. The Manhattan Project had answered the question of whether such a weapon could be built. It left humanity with the far harder question of what to do now that it existed.
1. What happened in August 1945, and how did the war end?
2. Why does the story say the project left "a far harder question"?
1. Atomic bombs were dropped on Hiroshima (6 August) and Nagasaki (9 August), killing tens of thousands, most of them civilians; Japan surrendered on 15 August, ending the Second World War.
2. Because building the bomb proved it was possible, but did not answer how humanity should live with such a weapon; other countries soon built their own, and the nuclear age began.
Read the story again and you'll notice how often it says what was done without saying who did it: the bomb was dropped, the towns were built, the work was kept secret. That is the passive voice — and it is no accident that history, science and news lean on it so heavily. It lets you put the action centre-stage and leave the doer in the background.
Rewrite the active verb as a passive one. Keep the same tense; you don't need to name the doer.
1. Scientists split the atom in the 1930s. → The atom in the 1930s.
2. The army built a secret city at Los Alamos. → A secret city at Los Alamos.
3. They have never settled the debate. → The debate settled.
1. was split (past simple passive: was/were + past participle)
2. was built
3. has never been (present perfect passive: has been + past participle)
Put the verb in brackets into the passive, in the tense the sentence needs.
1. More than a hundred thousand people (employ) on the project.
2. The material (must / produce) before the bomb could be assembled.
3. Today these weapons (still / hold) by several countries.
1. were employed (past simple passive)
2. had to be produced (modal passive: had to + be + past participle)
3. are still held (present simple passive)
Fill each gap with the given verb in whichever voice fits the note in brackets. Read the paragraph aloud when you're done.
The first device (detonate) before dawn in the desert (the action is the focus; the doer doesn't matter). Watching it, Oppenheimer (feel) that the world had changed (we want him as the subject). Later, the decision (take) to use the weapon (responsibility left unnamed on purpose).
was detonated (passive — the action matters, not who pressed the switch) · felt (active — Oppenheimer is the subject) · was taken (passive — the doer is deliberately left unsaid)
Notice how switching to the passive quietly removes the person responsible — which is exactly why it's so common when the subject is a difficult decision.
Hold on to this — in the Speak tab you'll retell the story, and the passive is the natural voice for describing what was built, tested and decided.
You've read the story and you have the words — so now the real thing is within reach. There's a full podcast episode that tells this story in much greater depth, in natural, real-speed English. It's optional: the lesson stands on its own without it.
From the Noiser podcast network. Hosted by historians, roughly 50 minutes. Open the show on Spotify and search "Short History Of The Manhattan Project" to find the episode.
Open the show on Spotify →This is the heart of the lesson — do all of it out loud. The timer is there to keep you going: fill the time with detail rather than rushing to the end.
Tell the story of the Manhattan Project in your own words, as if to someone who has never heard of it. Move through the arc: the discovery in Europe and the fear of Germany → Einstein's letter and the secret programme → the hidden cities and the Trinity test → Hiroshima and Nagasaki → the nuclear age that followed.
Narrate it in the passive voice wherever it fits ("the atom was split", "the cities were built", "the bomb was dropped", "the decision was taken"), and work in at least five key words (classified, unleash, chain reaction, refugee, blast, devastating, surrender, conscience, shadow).
The decision to use the bomb against Japan is still argued about today. Set out both sides as fairly as you can — the argument that it ended a terrible war quickly, and the argument that the deliberate destruction of two cities of civilians was never justifiable — and then say, carefully, where you stand and why.
Imagine you are a scientist invited to join a project like this. Talk through your thinking. Lean on the grammar: what would be built, what might be unleashed, what could be controlled afterwards.
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