Nettie Stevens: The Genetics Pioneer Who Discovered Sex Chromosomes

At a time when women mostly married and stayed home, or were teachers or nurses if they wanted to work, Nettie Stevens became a research scientist and her discoveries changed genetics forever.

NettieStevensGeneticsPioneerOnce she graduated with her PhD in 1903, she and a colleague (Thomas Morgan) began a collaboration on the controversial and unresolved question of how sex is determined in the developing egg. Did external factors, like food and temperature, set the sex of an egg? Or was it something inherent to the egg itself? Or was sex inherited as a Mendelian trait?

She examined the yellow mealworm, Tenebrio melitor, and made a striking observation. She had observed that this species produced two classes of sperm: a type that carried ten large chromosomes, and a type that carried nine large and one small chromosome. Body cells in the females contained 20 large chromosomes while males carried 19 large and one small chromosome.

Stevens reasoned that when an egg is fertilized by a sperm that carries the small chromosome, the result is a male offspring. The presence of the small chromosome might be what decided the individual’s “maleness.”

She published her research in 1905 and it eventually evolved into the XY sex-determination system we know today: The father’s sperm, which can carry either X or Y chromosomes, determines the sex of the offspring. Before Stevens’ work, scientists thought that the mother or the environment determined if a child was born male or female.

Biography

Nettie StevensNettie Maria Stevens was one of the first American women to be recognized for her contribution to science. Yet she didn’t begin her career in genetics until later in life.

Stevens was born on July 7, 1861, in Cavendish, Vermont, to Ephraim and Julia Stevens. After the death of her mother, her father remarried and the family moved to Westford, Massachusetts.

Initially, Stevens taught high school and was a librarian for more than a decade. Her teaching duties included courses in physiology and zoology, as well as mathematics, Latin, and English. Her first career allowed her to save up for college; at the age of 35, she resigned from a high school teaching job in Massachusetts and traveled across the country to enroll at Stanford University in California.

At Stanford, she received her B.A. in 1899 and her M.A. in 1900. She also completed one year of graduate work in physiology under Professor Jenkins and histology and cytology under Professor McFarland.

Stevens continued her studies in cytology at Bryn Mawr College, where she obtained her Ph.D. Here, she was influenced by the work of Edmund Beecher Wilson and by that of his successor, Thomas Hunt Morgan. Her work documented processes that were not researched by Wilson and she used subjects that he later would adopt along with the results of her work.

At age 50 years, only 9 years after completing her Ph.D., Nettie Stevens died of breast cancer on May 4, 1912 in Baltimore, Maryland.

Bring it Home

▶︎ Dive into Genetics with a fun unit study

▶︎ Enjoy a slide show presentation on genetics

▶︎ Try out this jigsaw format activity to explore the sex determination mechanisms of seven organisms, Xs and Os

▶︎ Learn about the Father of Genetics: Gregor Mendel

▶︎ Try this Gummy Bear Genetics lab from The Science Teacher (a NSTA publication)

▶︎ Use pipecleaners and beads to show how genes and chromosomes are inherited in this Pipecleaner Babies lab.

▶︎ Use pennies to do this How Well Does a Punnet Square Predict the Actual Ratios? lab.

Science Milestones

Visit my Science Milestones page to learn more about scientists whose discoveries and advancements have made a significant difference in our lives or who have advanced our understanding of the world around us.

The bloggers of the iHomeschool Network have teamed up to create fun and original unit studies on fascinating people who were born in July.

 

The Puzzling Impact of Ernő Rubik

For the past eight months there has been a constant click heard in my home. At the dinner table, while driving in the car, and even late at night when I am beginning to drift off to sleep, I can hear the subtle sounds of my son cubing. Cubing has become one of his passion projects and he spends every waking moment with a puzzle in his hands.

The Puzzling Impact of Erno Rubik @EvaVarga.netI had given him a traditional Rubik’s Cube a few years ago for Christmas but once it was scrambled, it sat in the corner of his bookshelf collecting dust. That was until he stumbled upon a recommended video on his YouTube feed of Collin Burns’ 5.25 world record solve. That was all it took. He was hooked.

As it is always in his hand, he gains a lot of attention and notoriety. He is now recognized around our community as the fastest cuber. Kids and adults alike bring him cubes that they “messed up” for him to solve.

His best solve time for the 3×3 is presently 7.22 seconds. He averages 13.09. Yet the 3×3 is not the only puzzle he enjoys. He also competes in 2×2, 4×4, 5×5, Megaminx, Pyraminx, and Skewb.

The Puzzling Impact of Erno Rubik @EvaVarga.netBiography

Ernő Rubik was born during World War II in Budapest, Hungary on the 13th of July 1944. His father, Ernő Rubik Sr., was a flight engineer at the Esztergom aircraft factory and a highly respected engineer of gliders. His mother, Magdolna Szántó, was a poet.

While Rubik has stated in almost every interview that he got his inspiration from his father, he also considers university and the education it afforded him as the decisive event which shaped his life. From 1958 to 1962, Rubik specialised in sculpture at the Secondary School of Fine and Applied Arts and later attended the Budapest University of Technology where he became a member of the faculty upon graduation.

“Schools offered me the opportunity to acquire knowledge of subjects or rather crafts that need a lot of practice, persistence and diligence with the direction of a mentor.”

In the 1970s, Rubik was a professor of architecture at the Budapest College of Applied Arts. It was during this time that he invented the Rubik’s Cube. The cube was originally designed to help Mr. Rubik explain spatial relationship to a class that he taught at the time. He soon realized the potential of the cube and began to get the cube mass produced, applying for a patent in 1975.

It was quickly a huge success. The cube was originally called ‘Magic Cube’ but after some discussion the name was changed to what it is known for today, Rubik’s Cube. In an interview with CNN, Rubik stated;

Space always intrigued me, with its incredibly rich possibilities, space alteration by (architectural) objects, objects’ transformation in space (sculpture, design), movement in space and in time, their correlation, their repercussion on mankind, the relation between man and space, the object and time. I think the CUBE arose from this interest, from this search for expression and for this always more increased acuteness of these thoughts…

In the nearly forty years the cube has been around, over three hundred and fifty million copies have been produced. Yet, only about 1.25% of the people who have purchased the cube can actually solve it.

The Puzzling Impact of Erno Rubik @EvaVarga.netErnő Rubik witnessed his creation blow up around the world. The cube became the Toy of the Year twice in a row, and the first world championship for The Rubik’s Cube was in 1982. At this competition the first world record was set at 22.95 seconds. Nowadays that is what most cubers average.

Today, there are a variety of speed cubes available on the market. Each is designed to turn faster and more efficiently without the lockups or pops that speed cubers abhor. The current 3×3 record is 4.737 seconds held by a 19 year old from Australia, Feliks Zemdegs.

Bring it Home

Learn to solve the original 3×3 puzzle using online tutorials; there are many to choose from.

Challenge yourself to get faster or learn to solve another puzzle type.

Visit the World Cube Association and find a competition near you to see what it is all about.

Science Milestones

Visit my Science Milestones page to learn more about scientists whose discoveries and advancements have made a significant difference in our lives or who have advanced our understanding of the world around us.

The bloggers of the iHomeschool Network have teamed up to create fun and original unit studies on fascinating people who were born in July.

10 Websites and Genealogy Resources for Kids

This past autumn, we enjoyed a family holiday on the East Coast of the United States and were thereby afforded with numerous educational experiences exploring our nation’s history. One of our most anticipated visits was to Ellis Island and the Museum of Immigration.
genealogy for kids

While here, we enjoyed a guided interpretive walk with a park ranger and thereafter enjoyed the many exhibits on our own. Amongst the highlights of our visit was seeing Norwegian bunad and langeleik, a stringed folklore musical instrument also known as a droned zither. As both my husband and I have Norwegian ancestors, seeing these personal artifacts brought the experience alive for us.

Genealogy Resources for Kids

Genealogy has always been fascinating to me. I grew up listening to stories my dad would share of his childhood and the stories that had been passed on to him by his Uncle Sam who had emigrated from Norway in the early 1900s. We’ve explored many of the branches of our family tree over the years. Today, I share some of our favorite genealogy resources for kids.

World’s Largest Online Resource for Family History

This is a subscription based, very user friendly site that is great even for a novice. This is the site I have used the most in my research. It includes records, links to other users, family trees, resources, pictures, and cemeteries.

Family Search

Family Search is a nonprofit family history organization maintained by the Church of Jesus Christ of Latter-day Saints. Since the Latter-day Saints are dedicated to preserving the records of their ancestors, they provide this service free.

Resources for Genealogists

Free database for genealogists that includes immigration, naturalization, military, passport, land, and bankruptcy records.

Researching Records and Archives

A low priced paid subscription web service that provides the user with an abundance of archived records of their ancestors.

Ellis Island History Center

Free immigration information for any ancestors that were processed through the Ellis Island and the Port of New York between 1892 and 1924, during their years of operation. Even if the relatives did not go through the port, it is an excellent source with links to other helpful sites.

genealogyforkidsGenealogy For Kids Forms

This site is geared for children with adult help. It has several links to forms kids can use, questions that they would find helpful while interviewing relatives and even a ‘cousin calculator’ that will help figure out how family members are related.

Genweb Project for Kids

This site is a good place for younger kids to start. It has links to several sites that would be helpful, however several of the links aren’t working. As with all internet usage, parental monitoring is needed.

Washington State Genealogy Resources for Kids

Excellent resource for students as well as adults with a wealth of information on researching the family tree.

Climbing Your Family Tree

This is an excellent source of worksheets for children to use when charting their family tree. It has PDF files to be used when interviewing family members.

Companion Website to be Used with the PBS Program Ancestors

An online companion to the series of 13 episodes presented by PBS on researching your ancestry. Each episode takes the viewer on a journey closer to finding their family’s story.

Science Milestones: The Heroine of Lyme Regis, Mary Anning

In my Facebook newsfeed recently, a memory popped up highlighting a field trip we took part in years ago when we first began our homeschool journey. Our visit to Paleo Lands Institute in Eastern Oregon is one of our fondest homeschool experiences. When we visit the Field Museum in Chicago last week, we reflected on this trip as we marveled at the many specimens they had on display – the most impressive, of course, was SUE (pictured below).

The unveiling of her 67-million-year-old skeleton at The Field Museum made global headlines in May of 2000. As the largest, best-preserved, and most complete Tyrannosaurus rex ever found, she is considered to be the most famous fossil ever found. She measures 40.5 feet long from snout to tail and 13 feet tall at the hip.

Interesting fact: While SUE is frequently referred to as a “she,” scientists don’t actually know her sex.

Virtually all parts of SUE’s skeleton are preserved in great detail—even the surface of her bones. Scientists can actually see where muscles, tendons, and ligaments once attached. Not only are most of the bones undistorted from fossilization, but cross-sections of the bones show that even the cellular structure inside remains intact.

w/ Sue at the Field Museum, Chicago

If SUE is the most famous fossil, who then is regarded as the most renowned fossilist the world ever knew?  The answer is Mary Anning.

Despite the fact that Mary Anning’s life has been made the subject of several books and articles, comparatively little is known about her life, and many people were unaware of her contributions to paleontology in its early days as a scientific discipline. How can this be, you ask?

Biography

Mary Anning by B. J. DonneMary Anning was born on the 21st of May 1799 to Richard and Mary Anning in Lyme Regis, Southwest England. Mary grew up in a prime location to lead a life of fossil collecting. The marine fossil beds in the cliffs in this area remain today a huge source of fossils from the Jurassic period.

Her findings contributed to important changes in scientific thinking about prehistoric life and the history of the Earth. At the age of 12, Mary Anning was to become one of the most famous popular palaeontologists, with her discovery of a complete Icthyosaur.

Interesting fact: Though she is now credited with the discovery, her brother had first found the specimen. Mary did find the majority of the remains and contribute significantly to the excavation work. Mary went on to find two more species of Ichtyosaur in her life.

In early 1821, Anning made her next big discovery with the finding of the first Plesiosaurus. She sent a drawing she made to the renowned George Curvier, who at first snubbed it as a fake. Upon further examination, he eventually reversed this statement finally giving Anning the respect she had deserved from the scientific community. This discovery is perhaps her most important find, from a scientific point of view.
Autograph letter concerning the discovery Wellcome L0022370
The majority of Mary’s finds ended up in museums and personal collections without credit being given to her as the discoverer of the fossils. There are many factors contributing to this error: the lack of appropriate documentation of her special skills, her social status, and more importantly, her gender. Many scientists of the day could not believe that a young woman from such a deprived background could posses the knowledge and skills that she seemed to display.

For example, in 1824, Lady Harriet Sivester, the widow of the former Recorder of the City of London, wrote in her diary after visiting Mary Anning:

“. . . the extraordinary thing in this young woman is that she has made herself so thoroughly acquainted with the science that the moment she finds any bones she knows to what tribe they belong. She fixes the bones on a frame with cement and then makes drawings and has them engraved. . . It is certainly a wonderful instance of divine favour – that this poor, ignorant girl should be so blessed, for by reading and application she has arrived to that degree of knowledge as to be in the habit of writing and talking with professors and other clever men on the subject, and they all acknowledge that she understands more of the science than anyone else in this kingdom.”

After her death on the 9th of March 1847, her unusual life story attracted the attention of scholars around the world. Her story was the inspiration for the 1908 tongue-twister “She sells seashells on the seashore” by Terry Sullivan and in 2010, one hundred and sixty-three years after her death, the Royal Society included Anning in a list of the ten British women who have most influenced the history of science.

Bring it Home

➤ For younger students, explore the fun games and activities at BBC’s Primary History Famous People: Mary Anning.

➤ Read the article, “Mary Anning: The Fossilist as Exegete” by Thomas W. Goodhue in Endeavour Magazine, March 2005 issue

➤ Build upon your child’s interest in fossils and geology in an in-depth Earth sciences curriculum study.

Geology Rocks➤ Visit a local geology club in your area and inquire about getting started in collecting.

➤ Discover Ice Age Fossils at La Brea Tar Pits in Los Angeles

 

Science MilestonesVisit my Science Milestones page to learn more about scientists whose discoveries and advancements have made a significant difference in our lives or who have advanced our understanding of the world around us.

Interested in learning about others who were born in the month of January? Hop over to Birthday Lessons in March to read posts by other iHomeschool Network bloggers.

More Than Just the Telephone: The Impact of Alexander Graham Bell

Unbeknownst to many, Alexander Graham Bell made outstanding contributions to aviation through his development of tetrahedral kites, the investigation of their application to personnel carrying aircraft, and his enlistment of talented associates who aided significantly in the progress toward accomplishing powered flight.

Expanding upon the design of the rectangular-celled box kite that Hargrave of Australia invented, Dr. Bell developed a three-sided triangular form of cell which he adapted to various multi-cellular shapes. This research led to a large kite in which on December 6th, 1907, his associate, Lt. Thomas Selfridge, flew to a height of over 160 feet.

Science Milestones: Alexander Graham Bell @EvaVarga.netAlthough his greatest scientific accomplishment was the invention of the telephone, Dr. Bell deserves wide recognition for his promotion of aeronautics. He was a member the Aerial Experiment Association that formed in 1907 who conducted flight experiments from his summer home at Baddeck, Nova Scotia.

“I have no doubt that a machine will be driven from the Earth’s surface at enormous velocities by a new method of propulsion – think of tremendous energies locked up in explosives – what if we could utilize these in projectile flight!” ~ Alexander Graham Bell

Believing that the substitution of an engine and propeller attached to the kite might permit free man-carrying flight, dispensing with the tethering line, Dr. Bell and Lt. Selfridge secured the services of Glenn H. Curtiss. Curtiss helped them to construct a proper engine, and they also engaged the assistance of J. A. D. McCurdy and F. W. Baldwin. These five men formed the Aerial Experiment Association for the stated purpose of “getting into the air” – which also put them in direct competition with the Wright brothers.

Biography

Science Milestones: Alexander Graham Bell @EvaVarga.netAlexander Graham Bell was born on March 3, 1847 in Edinburgh, Scotland. His mother was the daughter of a Royal Navy surgeon and was a skilled musician and portrait painter whose hearing loss when Bell was just twelve years old, brought deafness close to him.

Bell’s father, Alexander Melville, was the world world-famous inventor of “Visible Speech”, a code of symbols to guide the action of the throat, tongue and lips in the shaping of various sounds. It was devised as a key to the pronunciation of the words in all languages, but had become of most use in teaching the deaf to speak. His grandfather, Alexander, was a specialist in the correction of speech defects as well as a renowned public speaker, giving public readings from Shakespeare’s plays on London’s stages.

“Don’t keep forever on the public road, going only where others have gone. Leave the beaten track occasionally and dive into the woods.” ~ Alexander Graham Bell

Bell had natural musical ability and turned toward a career as a pianist. By the time he was 25, he was assisting his father at Weston House, a boys’ school near Edinburgh, and trading music and elocution lessons for instruction in other subjects. He continued his formal education at the University of Edinburgh and later specialized in the anatomy of the vocal apparatus at University College in London. At 22, with his formal education behind him, he became a partner with his father.

He moved with family to Ontario in 1870 and a year later Sarah Fuller, the principal of a school for the deaf in Boston, asked him to teach her teachers. His success lead to a professor appointment at Boston University.

Bell’s patent for his telephone was filed just two hours before another experimenter, Elisha Gray, filed his claim in the U.S. Patent Office.

While in Boston, Bell met the two men who financed his pioneer work with the telephone. Thereafter, Bell spent the latter part of his life in Washington, D.C. and his summer home in Nova Scotia. He became a United State citizen in 1882.

He died on August 2, 1922 at which time 14,347,000 telephone were in operation across the country.

Bring it Home

➤ Research and discuss the invention of the telephone, its origin, its innovations, its advantages and disadvantages, and how it has shaped today’s society.

➤ Watch a video about Alexander Graham Bell.

➤ Create a poster to illustrate the changes the telephone has undergone since Bell’s original invention.

Build a tetrahedral kite of your own. Test the flight and refine your design to make improvements.

➤ Research his contemporaries (Glenn Curtiss, the Wright brothers, Thomas Edison, etc.) and put together a presentation (PowerPoint, brochure, poster, video, etc.) to share with others their impact on technology.

➤ Although Bell is best known for inventing the telephone, he invented many other things. He held patents for 18 other inventions on his own and 12 for which he collaborated with others. Learn more about each of these.

Science Milestones

Visit my Science Milestones page to learn more about scientists whose discoveries and advancements have made a significant difference in our lives or who have advanced our understanding of the world around us.

Interested in learning about others who were born in the month of January? Hop over to Birthday Lessons in March to read posts by other iHomeschool Network bloggers.

Ever Wanted to Visit Switzerland? Now You Can With Case of Adventure

Travel has always been a major part of our homeschool lifestyle and we consider ourselves to be World Citizens. We do our best to immerse ourselves in other cultures while also learning more about our own nation’s rich history and geography. When I learned of the opportunity “to travel to Switzerland” with the CASE OF ADVENTURE Switzerland Unit Study, I knew it was the perfect fit for us.

Cuckoo Clock Secrets in Switzerland unit study @EvaVarga.net

Whether your family enjoys traveling or has never traveled overseas, you’ll love how Cuckoo Clock Secrets in Switzerland makes learning come alive.

Cuckoo Clock Secrets in Switzerland is the first book of the CASE OF ADVENTURE travel series. It centers around a homeschool family that travels regularly. Upon reading the first chapter, your kids will dive into adventure with Ren, Rome, Jake, Libby and Tiffany as they discover an ancient coin and a mystery connected with a cuckoo clock which takes them to the beautiful land of Switzerland. In their quest to solve the puzzle, they unearth some fascinating history and recover a lost fortune.

Switzerland Unit Study Resources & Ideas

We’ve have always had an eclectic, Unschooling approach to educating our children. Many of our most enjoyable learning experiences have been unit studies using a novel as our spine.

Some of our past unit studies include:

We thereby relished in the opportunity to explore Switzerland in a unit study based on the novel Cuckoo Clock Secrets in Switzerland. It was a relaxed way to stay engaged in academics through the holidays.

I began each morning reading aloud a chapter or two and then the kids would dive into the investigation suggestions (IDAs) at the end of each chapter. Several videos related to the content were suggested for each chapter. We thereby learned how cuckoo clocks were made, how ropes are made for mountain climbing, relative distances, the Protestant Reformation in Switzerland (a huge part of the mystery), and the process of cheese making.

Huge metal vats of curds and whey were stirred with big metal arms and the curds cut into small blocks with wire slicers and then reheated. 

“How does the milk change into cheese?” asked Rome of Frau Von Allmen. 

“They add a culture to the milk. The culture is a bacteria which changes the cheese as you heat it,” she replied. 

cheese factoryUpon reading about the family’s visit to the large cheese houses in the village of Gimmelwald, we revisited our own experience in cheese making at a local cheese factory. Inspired, we also enjoyed making cheese fondue and sampling a variety of Swiss cheeses we found at our local grocer.

To coordinate with our science studies, I asked each of the kids to write an expository essay describing how a cuckoo clock functions – describing the simple machines within. As I shared our activities with family over the holidays, we learned that Grandma Raandi (my mother) has one she says needs a little repair that she would be willing to give us. We haven’t yet got our hands on it (she doest live locally), but we look forward to applying our new knowledge soon. We’ll keep you posted. :)

I love how living books can encourage further investigations and explorations of topics. Following these little rabbit trails are what make homeschooling so unique. After immersing ourselves in the Cuckoo Clock Secrets, it is no wonder that Switzerland has now bumped up on our “must see” countries list.

Switzerland Lapbook Activity Packs & Printables

If you are pressed for time or if you are inexperienced in putting together a unit study of your own, CASE OF ADVENTURE makes it easy. In addition to the great novel, they have also put together a wealth of activities and downloadable resources. Destination Switzerland is available now and Scotland will be available soon.

Switzerland Unit StudyVisit CASE OF ADVENTURE to purchase the Destination Switzerland Unit Study as well as download the FREE Maps Pack and Money Pack to use for your geography studies. You will also find the Mega Travel Activity Pack that goes along with any novel in their series. Filled with spy gear and codes – this activity pack will bring the mystery to life, especially for younger kids.

My kids have never been very keen on lapbooks and we don’t have a color printer. Thus, what I appreciated best in the activity packs was the teacher manual which provided all sorts of amazing tips and suggestions for integrating Switzerland studies into our daily activities.

Worldview: CASE OF ADVENTURE is not a fully secular curriculum. There is mention of Christianity, bible study, and prayer but the curriculum and activities that accompany the novel are not a Bible curriculum.

Connect with CASE OF ADVENTURE

Follow CASE OF ADVENTURE on Facebook and Instagram to learn of future titles and activity ideas. You will also find them on Pinterest. If Twitter is more your style, follow Karyn Collett, the author.

Take advantage of the Special Launch Discount of 25% off entire cart for 10 days only – use coupon code: 25LAUNCH (February 1-11, 2017) or enter to win

Please note the discount is applied to the downloadable products only, not the print book from Amazon.