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; Oakridge, TN; and 

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

during World War II. Every location has different stories to share. 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 

Oakridge, TN 

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. 11.21.2016 

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). It claimed more lives than any 

previous war. In the United States, men and women from all cultures worked together to 

win the war. 

It all started when Nazi Germany’s leader, Adolph 

Hitler, invaded Poland. Britain and France declared 

war on Germany two days later. 

On December 7, 1941, (now called Pearl Harbor Day), 

Japan’s Imperial Army made a surprise air attack at 

Pearl Harbor, Hawaii, USA. The attack drew America 

into the war. 

America knew it had to create better weapons. Afraid that Germany might make the first 

atomic weapon, the U.S. hired scientists to start work on a 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 science mission. Los Alamos, New 

Mexico was chosen as the main site for a new atomic bomb laboratory. The lab was given 

the code name “Project Y”. It was in New Mexico where scientists made and tested the first 

nuclear weapons in the world during WWII. The use of these weapons ended the 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?___________ 

Why/Why not?_____________________________________________________________________ 
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. 

4 
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 Puebloans were hired to work on the Manhattan 

Project. This changed their culture from a barter system to a cash economy.

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 “Townsite 

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. 

5 

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), Director of the Los Alamos Laboratory, and Army Lt. General Leslie Groves 

(right) were the leaders at Los Alamos. Groves was the 

Officer in Charge overseeing all military and civilian 

phases of the project. Oppenheimer recruited the scientists and also helped to choose the project’s secret 

location. He is often called the "father" of the atomic 

bomb. 

Scientists such as Norris Bradbury and Hans Bethe 

worked with the Army Corps of Engineers, often 6 

days a week, on weapons planning and the rapid 

creation of an atomic bomb. 

The Regular Army and the Women’s Army Corps (WACs) 

provided the necessary services to keep Project Y safe and 

secret. Military Police provided screening at the entrance 

gate and security escorts within the city. WACs performed 

important work in communications, purchasing supplies 

and transmitting scientific data in a top-secret environment. 

6 

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. 

To join the Manhattan Project, scientists agreed to become part of top-secret war research 

in an unknown part of the country. When they arrived at their first stop near Santa Fe, a 

gatekeeper named Dorothy McKibbin told them their journey was not over. She gave them 

passes to enter the city and arranged transportation up a dirt road to their new homes. 

The Los Alamos site was surrounded by a fence. Everyone’s mailing address was the same: 

PO Box 1663, Santa Fe, NM. All who lived there had to keep their location, jobs and lives a 

secret. Scientists and their families tried to live normal lives, but they could not tell anyone 

where they were or what they were doing. Some common activities included going to movies, skiing, hiking, horseback riding and dancing. 

Even children had to have a special ID card to live 

in the town. 

 Kids went to school, played games and 

lived in homes just like you, but they could 

not tell friends or family outside of the town 

anything about their lives. 

7 

Can you keep a secret?_____________ 

How do you think it would feel to live in a secret place?_________________________________ 

Why do you think it was important to keep the city a secret?_____________________________ 

Do you think talking about the activities they did could expose their secret location?_______ 

Why or Why Not?__________________________________________________________________ 

Courtesy of the Los Alamos Historical Society Archives 

Courtesy of the Los Alamos Historical Society Archives 
Imagine you live in a Secret City and 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. Write a letter telling them about your day, but 

keep your location, the other people who live there and what they 

are doing a secret. What things do you think you can write about? 

8 
Scientists discovered that when atoms 

are smashed together (Fusion), or 

split apart (Fission), they create 

energy. 

Energy can be used in an atomic bomb 

or to make electricity for your home. 

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 __ __ __ __ __ __ __ . 

Energy 

is 

the 

ability 

to do 

work. 

 Nuclear fusion Nuclear fission

 

Small atom 

 

 Small atom 

 

Energy Energy 

 Large Large 

 atom atom 

Small atom 

 Small atom 

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. 

9 
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 _________. 

10 
P D R F B K L J S D F G H U K M N H Y T G V D W E S 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Y R E F G A S O V G Y J J T F D E R P E I U Y L I Y 

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! 

11 
 

_______________________________ 

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 
P D R F B K L J S D F G H U K M N H Y T G V D W E S 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Y R E F G A S O V G Y J J T F D E R P E I U Y L I Y 

       2         

     1 u r a n i u m    

      o              

    3 a t o m    4        

     5    s    6 t r u m a n

     j e     a        

     a v     d     

      7 o p p e n h e i m e r

    a    l       a      

8 t r i n i t y     t     

              9 s c i e n c e

             o        

         10 e n e r g y

Word Search Key

Crossword

Atomic Science  

Fill‐in‐the‐Blank Key

1. atoms

2. energy

3. fission

4. protons

Timeline

P   R   O   J   E   C   T   Y