Manhattan Project National Historical Park 

 Los Alamos, New Mexico 

National Park Service 

U.S. Department of the Interior 

MAIN	GATE	 	

PASSES	MUST	BE		

PRESENTED	TO		

GUARDS	

Manhattan Project National Historical Park 

Los Alamos, New Mexico 

JUNIOR RANGER BOOK 

PASSES	

POST			

		No.	1	

SECRET	

Courtesy of the Atomic Heritage Foundation 
Manhattan Project National Historical Park is a partnership park between the 

Department of Energy and the National Park Service. 

Three separate sites were located in Los Alamos, NM; Oak Ridge, TN; and 

Hanford, WA. Each site contributed significantly to scientific study and defense 

during World War II. Download Junior Ranger books from other sites to learn 

more! 

Junior Rangers are a very special group of people who promise to care for our National 

Parks so that future generations can enjoy and learn from them too! To become a Junior 

Ranger, you will need to read information about the Los Alamos Manhattan Project site, 

answer questions and complete activities. It is OK for parents to help! When you are 

finished, bring the completed booklet to the visitor center, or mail it in to the address 

below to receive your badge. Please tell us where to mail your badge: 

 Name _______________________________________________ 

 Address _____________________________________________ 

 City ________________________________________________ 

 State __________________________ Zip _________________ 

For questions, contact the Los Alamos, NM Visitor Center at: 

475 20th Street, 

Los Alamos, NM 87544 

(505) 661-6277 

Visit us online at www.nps.gov/mapr 

Check out our Facebook page: www.facebook.com/ManhattanProjectNPS 

Also find us at Twitter@MnhtnProjectNPS 

Oak Ridge, 

Los Alamos, NM 

Hanford, WA 

How many pages do I 

complete to earn my badge? 

9th grade and up - All pages 

4th-8th grade - 5 pages 

Under 4th grade - 3 pages 

Rev. 8/2017 2 
3 

World War Two (WWII) was the biggest war in history, fought between 

1939 - 1945. 

The Axis Powers (Germany, Italy, Japan and 8 other countries) fought against the Allied 

Powers (France, Britain, Russia, U.S. and 57 more 

countries). In the United States, men and women 

from all cultures worked together to win the war. 

It all started on September 1, 1939 when Nazi 

Germany’s leader, Adolph Hitler, ordered the 

invasion of Poland. Britain and France declared war 

on 

Germany 

two days 

later. 

On December 7, 1941, (now called Pearl Harbor 

Day), Japan’s Imperial Navy Air Service made a 

surprise air attack at Pearl Harbor, Hawaii, USA. 

The attack drew the U.S. into the war. 

The U.S. decided it had to create better weapons to end the war. The U.S. hired scientists to 

start work on a very special bomb. Secret sites were located in Manhattan, New York, to 

study how to create atomic weapons. The first secret headquarters base was in a skyscraper 

hidden in plain sight - right across from City Hall! The “Manhattan Project” was named 

after the start up location of this scientific mission. Los Alamos was chosen as the main site 

for the new laboratory named “Project Y”. They helped end this terrible war. 

Why do you think this conflict was called a “World War”? _______________________________ 

The Manhattan Project had this name because _________________________________________ 

Would you like to be a scientist working on a secret mission for the government?___________ 
Fill in the Blanks 

1. The basic building blocks of matter are called __ __ __ __ __ . 

2. Scientists harnessed the power of the atom to create __ __ __ __ __ __ . 

3. Splitting the atom is called nuclear __ __ __ __ __ __ __ .

4. The nucleus of the atom has neutrons and __ __ __ __ __ __ __ . 

In 1945, the first atomic bomb was made by studying the new field 

of nuclear science - the study of the atomic world. 

When scientists need to find answers to hard questions, 

they conduct experiments. New experiments proved 

what scientists had long suspected - All matter in the universe is made up of atoms! Atoms are tiny particles that are 

too small to see. They are the basic building blocks of all 

things! 

Scientists discovered that when atoms are smashed 

together (Fusion), or split apart (Fission), they create a 

lot of energy! Energy is the ability to do work. And the 

energy from atom smashing or splitting can be used to 

create a bomb or power your house. 

4 
Put the letters in the circles on the timeline in order by 

date. Start with the earliest date first to spell the code 

C 

The new, secret town 

of Los Alamos is built 

in 1943. 

J 

The Imperial Japanese Navy 

attack Pearl Harbor, Hawaii 

on 

December 7, 1941. 

The U.S. Declares war on Japan. 

E 

The secret operation called the Manhattan Project began in 1942.

R 

Hitler invades Poland September 

1939 beginning WWII 

O 

Plutonium was discovered in 1940 by 

scientists studying how to split atoms to 

make atomic bombs. Plutonium is created in 

a reactor when uranium atoms absorb neutrons. 

P 

X-rays are discovered in 

1895 by 

Wilhelm Roentgen. 

Y 

Manhattan Project is 

made a National 

Historical Park in 

2015. 

T 

The US successfully tested an atomic 

bomb and then used atomic bombs over 

the Japanese cities of Hiroshima and 

Nagasaki in 1945. 

5 
The Manhattan Project chose this site because of its isolation, but the government had to 

acquire land belonging to people living there. Some older buildings belonged to the Los 

Alamos Ranch School, a prestigious college prep school, which trained boys in outdoor and 

ranching skills. 

Homesteaders, mostly Hispanos, were also made to sell their land to the government for 

little payment. Many local Hispanics and Native Americans were hired to work on the 

Manhattan Project. 

The Romero Cabin belonged to homesteaders. 

They raised crops and grazed livestock here in 

the summers. 

Many years after selling their homestead to the 

government, this cabin was moved downtown. 

You can see this old cabin along the “Town site 

Properties Walking Tour” behind Bathtub Row. 

Los Alamos (the cottonwoods) sits on 

Pajarito (little bird) Plateau. Native 

Americans lived here over 10,000 years 

ago. Some Pueblo ancestors built stone 

houses and cliff-dwellings here around 

800 years ago. 

Many of their descendants now live on the 

nearby Santa Clara and San Ildefonso 

Pueblos. You can see the ancestral Pueblo 

dwelling sites beside the old Romero 

Cabin. 

6 

Why did the Manhattan Project select this location?_______________________________ 

How would you feel if you had to leave your home? _______________________________ 

Do you think the government was right to take people’s land?_____________ 

Why or why not?___________________________________________________________ 
Robert Oppenheimer (left), Scientific Director of the Manhattan Project and Army Lt. 

General Leslie Groves (right) were the leaders 

at the Los Alamos secret location. 

The Regular Army and the Women’s Army 

Corps (WACs) performed important work in 

communications, purchasing supplies and 

transmitting scientific data in a top-secret 

environment. 

7 

Which group described above would you choose to work for?_________________________ 

Why?___________________________________________________________________________ 

Los Alamos was a unique community that combined ordinary civilians, scientists, 

engineer detachments, and the military to work together to develop an atomic bomb. 

Local civilians able to pass intense security 

clearances were issued passes to enter the 

project area. They performed construction, 

maintenance, housekeeping and other service 

positions within the secret city. 

Courtesy of the Los Alamos Historical Society Archives 
From 1943 to 1945, Los Alamos was a top-secret army 

post isolated from the world and the home of Project Y. 

The Los Alamos site was hidden by a fence that surrounded the city. Everyone’s location and jobs had to be 

a secret. 

Even children had to have a special ID card to live 

in the town. Kids went to school, played games, went 

horseback riding and lived in homes just like you, but 

they could not tell friends or family outside of the town 

8 

Courtesy of the Los Alamos Historical Society Archives 

Imagine where you live is a secret town and you are writing a letter to someone 

who does not live there with you. You can write to a friend, relative or even a 

pen-pal. Tell them about your day, but keep your location, the other people 

who live there and what they are doing a secret. 
Word Bank 

 

 atom energy 

 uranium radiation 

 Oppenheimer science 

 Truman Roosevelt 

 Japan trinity 

        2         

        1        

             

      3         4     

    5     6         

            

                  

    7             

 

  8         

               9 

               

               10 

 

Down 

2. When World War II began, the U.S. 

 President was Franklin D. ________. 

4. After the atomic bomb was dropped 

on Japan, many people suffered the 

terrible effects of __________ 

 sickness. 

5. An island nation off the east coast of 

 Asia that bombed Pearl Harbor, 

 Hawaii, causing the United States to 

 enter World War II. 

Across 

1. A radioactive element (U92) used to create atomic bombs and to fuel nuclear reactors. 

3. Smallest bit of matter made of protons, neutrons and electrons. 

6. U. S. President, Harry S _________ made the difficult decision to drop two atomic bombs on Japan. 

7. The scientist at Los Alamos who headed efforts to develop the first atomic bomb was J. Robert _____. 

8. Name of the test and test site for the first atomic bomb detonation. 

9. The Manhattan Project required the accumulated knowledge of many branches of physical _______. 

10. A nuclear weapon releases great amounts of thermal _________. 

9 
D A D E R F V B D A N H U K L O N W E A P O N 

G J C V B M H I J T M N V C D D O T G G B N J 

Q N Q C V B F R G O S D F G H R I B N M K J N 

Z S B G Y U J K L M B H M I U Y S R D F V G T 

B A S D F N O R R I S B R A D B U R Y C I U O 

M S Z X C V B N M C E B O V C X F W E R R G T 

L X C V B N X D V B C G B J K L M G D I S B F 

O V G Y J J T F D E R P E I U Y T F A T M A N 

F U L L E R L O D G E O R A S D F G H I J K L 

P R X S D C V B N M T L T O T O P S E C R E T 

I A X C D R F T E R L G O I J L M J I A P R I 

N N C V B N M R I K A L P U L E I O P L U H E 

T I X C V B N I N M B N P V I X C Z C I E O Q 

Y U L V D W E N R G O U E K S S M T P T O U U 

F M S O D F G I H J R K N H O G S F Y Y D S E 

B Q O I S Y T T F G A H H K T L O L N B V E D 

D F G H W A D Y C V T O E P O W M I O I J H V 

X V B N N H L G F S O D I S P E S D F T G H J 

C Q X C V B N A B N R N M P E C E D F S I T Y 

E W E R T Y I D M P Y I E D T G S W E F V N N 

R E W A R D O G P O H J R A D I O A C T I V E 

T S A G T D E E K O S L P O V U R B N DI U M R 

Y A X W I U N T T J M L P E C D S W E D C V F 

E W O R L D W A R I I S E D T G S W E F V N N 

Atomic              Los Alamos                    Secret Laboratory

Baker House            Louis SloƟn                    Top Secret

CriƟcality              Norris Bradbury          Trinity Gadget

Fat Man              Project Y            Uranium

Fuller Lodge            RadioacƟve                    Weapon

Fusion               Robert Oppenheimer                World War II

Los Alamos was a hidden city with a secret laboratory where weapons were being created for 

defense in World War II. The words below are related to the town, the scientists, buildings 

and the important work they did to make an atomic bomb before Germany could complete 

one. Search for the secret words below. Look in all directions! 

10 
 

_______________________________ 

For completing the 

Manhattan Project 

National Historical Park 

Junior Ranger Activity Booklet 

Los Alamos, New Mexico 

Official Park Date Stamp 

As a Junior Ranger of the Los Alamos Manhattan Project 

National Historical Park, I promise to learn more about the 

science and history of the Manhattan Project and World War II. I will explore 

many more National Parks and help to protect 

and preserve them for future generations.

Park Ranger Name