For centuries people have wondered who was the model for Leonard do da Vinci’s Mona Lisa and what was the reason for her smile. But the Mona Lisa is just one of the many mysteries in the art world. Here are some other notable unsolved art mysteries that might be a little less familiar.

Mystery 1: Who Is the girl in Johannes Vermeer’s Girl with a Pearl Earring?

Around 1665, Dutch artist Johannes Vermeer painted a charming portrait of a young girl. People around the globe have long wondered who this fetching young lady was. Many say she must have been Vermeer’s daughter or girlfriend. Others think she wasn’t a real person, but rather an intentionally mysterious, timeless figure. The painting, referred to as the “ Mona Lisa of the North ” , has been part of The Hague’s permanent collection since 1903. But it draws record-breaking crowds whenever and wherever it tours around the world.

Mystery 2: Where Is Raphael’s Portrait of a Young Man?

Portrait of a Young Man is considered one of the most important pieces of art to go missing during World War II. The painting was created around 1513 by Raphael, a famous Italian Renaissance artist, and stolen from Poland’s Princes Czartoryski Museum in 1939.

The portrait had traveled to Germany and Austria before it was gone in 1945.

Mystery 3: Was Van Gogh Murdered?

One of the main things people know about Vincent van Gogh is that he cut off his ear. That was likely because the Dutch post-impressionist painter suffered from mental illness, probably severe depression. The official cause is suicide from a gun shot at close range.

That certainly seems plausible (貌似有理的), given his poor mental health. However, no gun was found near his body, and locals reported two teenage boys bullying him shortly before his death.

Free Online Drawing Classes

Drawing is a skill you can learn at any age. When you are ready, you can learn the basics of drawing by taking one or more of the free online drawing classes offered here. The websites all offer helpful instruction for beginning artists, and many of them offer classes at intermediate (中级的) or high levels. When you use the websites as your art instructors, you can log on to learn whenever you please.

Artyfactory

The Artyfactory Art Lessons Gallery offers free online art lessons that include basic drawing classes for pencil, ink and colored pencil. For visitors who want to expand their knowledge of art, the site also offers an Art Appreciation Gallery and a Design Lessons Gallery.

Academy of Art University

This free video class from the Academy of Art University called “How to Draw a Head” teaches you how to draw a head from a photo or from memory. The instruction is mainly on facial proportion (比例), expression and drawing basics.

How to Draw It

The How to Draw It website offers a simple approach to drawing animals and people. The animal tutorials (教程) are super easy to do, while the people lessons are a bit more difficult. All are free to visitors and making fast progress in your drawing skills is possible.

Free Online Art Classes

This site covers a range of art classes, but there are several free drawing tutorials for online learners, including: Learn Basic Drawing, Draw with Pen and Ink, and Learn Colored Pencils. Some of the classes are downloadable and some are in video form.

A kiln (窑) is a type of oven or furnace used to cure, harden, or burn certain materials. Depending onwhich materials are heated in it, a kiln may be square, tunnel shaped, or beehive shaped, and usually madeof brick or stone.       【小题1】 It may be set as low as sixty-five degrees to cure grain or as high as 3,200degrees to transform limestone to quicklime (熟石灰).

【小题2】They have a variety of purposes. The cement(水泥) industry uses revolving kilns to heatand separate raw materials. Bricks, pottery, and china made from clay must be fired, or hardened, in kilns.Certain kinds of coal and wood must be kiln-dried before they can be used. Hobbyists use small kilns tofire a variety of ceramic(陶瓷) objects.

There are two main types of kilns. A periodic kiln, used to fire certain kinds of delicate china, is raisedto a high temperature and then completely cooled before its contents are removed. A continuous, or tunnelkiln contains several chambers, or zones, which heat, bake, and cool a product. Stacks of clay bricks movethrough a tunnel kiln on tracks.   【小题3】

Gas, oil, and coal are all used to heat modern kilns.     【小题4】 But for special jobs, where cleanlinessand careful heat are important, kilns must be heated by electricity oven though it is more expensive. Smallkilns used in the home or in craft shops are also heated electrically because electricity is clean andconvenient.

【小题5】 When ancient people discovered that heat hardened some materials, they were able to makedurable household objects such as jugs and bowls. Today our museums display many kinds of ancientstatues and art objects that have lasted because they had been kiln-dried. They come from lands as far apartas China and Greece.