What are the quantitative relationships between the substances in a chemical reaction? The study of stoichiometry shows you how to apply your ability to balance equations to solve problems involving chemical reactions.

Thoughts and responses to themes of "Loss & Desire" surface in many areas of our lives, from the philosophical to the emotional. In this episode, specific works of art cause us to contemplate issues such as war and peace; the loss of community and the desire for connection; and the age-old human longing for perfection.

"Time" is always present in our interaction with works of art, whether we sit to contemplate a painting, stroll past a sculpture, or watch a video piece for its entire duration or cycle. Some works of art are time-based in that the viewer must experience them through the passage of time, as with music, while others refer to time through links or references to art history, our collective human history, or the timelessness of nature. Filmed on location in China; Japan; New York, New York; San Antonio, Texas; Cambridge, Massachusetts.

The four artists profiled in "Humor" have been influenced by the history of humor and comedy, including vaudeville, cartoons, and comic books. The artists in this hour reveal how humor and satire can stimulate laughter as well as serve as a vehicle to explore serious subjects, such as feminism, the natural environment, the excesses of consumer culture, social injustice, and war.

From politics to mass media, the theme of power pervades daily life. The artists in this program -- Cai Guo-Qiang, Laylah Ali, Krzysztof Wodiczko and Ida Applebroog -- negotiate personal and cultural histories, re-imagine social space and challenge authority, oppression and control. The hour concludes with an original piece of video art by Teresa Hubbard/Alexander Birchler. David Alan Grier hosts.

How does memory function? Who creates history? Whether commemorative, critical or irreverent, the artists in episode two - Susan Rothenberg, Mike Kelley, Hiroshi Sugimoto and Josiah McElheny - delve into the past, transforming it and remaking it in their work. The hour concludes with an original piece of video art by Teresa Hubbard/Alexander Birchler, a unique and poetic meditation on the idea of memory. Isabella Rossellini hosts.

How do we organize life? What are the ways in which we capture knowledge and attempt greater understanding? The artists in this episode - Mathew Ritchie, Fred Wilson, Richard Tuttle and Roni Horn - create systems, shift contexts and engage with perception, utilizing unconventional devices. The hour concludes with an original piece of video art by Teresa Hubbard/Alexander Birchler, a unique and poetic meditation on the idea of structures. Sam Waterston hosts.

Spontaneous, funny or subversive, play can take many forms. The artists in this episode - Jessica Stockholder, Ellen Gallagher, Arturo Herrera and Oliver Herring - improvise games, draw inspiration from dance and music, and employ color, pattern and movement to induce delight. The hour concludes with an original piece of video art by Teresa Hubbard/Alexander Birchler, a unique and poetic meditation on the idea of play. Grant Hill hosts.

The documentary shot in Poland, Ukraine and Israel tells the story of Shimon Redlich, a Holocaust survivor who returns to places from his childhood as well as different hiding places in his struggle to survive. A collector of memories and a seeker of good will, Shimon takes us on a journey through Poland and Ukraine, uncovering the brighter sides of dark times. The film also employs archival footage from the 1948 Yiddish film "Unzere Kinder", where Shimon had a role as a child actor.

"Coming Out Polish Style" offers a rare look into the lives of gays and lesbians in contemporary Poland. The film explores the issue of gay and lesbian rights in a conservative society, which is undergoing a very dynamic transformation, allowing for more and more successful liberal changes. The documentary focuses on the diverse and complex identity struggles involved in the process of 'coming out'. It profiles both celebrities who are openly gay in Poland, as well as young people from small towns who are still in the process of 'coming out'. There may be as many as 2 million gays and lesbians living in today's Poland. However, the majority of them are still 'in the closet'. During the past severals years, a number of Polish celebrities, among them artists and journalists have come out as homosexuals. For some, being gay or lesbian no longer causes 'a problem'. Despite a general change in attitudes, regular young people who decide to 'come out' on the most part go through a painful process, which often involves discrimination, rejection or contempt. Despite existing signs of homophobia, young Polish gays and lesbians are finding more and more friendly clubs to attend, and there is a determined core of activists pushing for gay rights at the national level. In 2010, Warsaw hosted the largest European Gay Pride Parade - EUROPRIDE. Thousands of gays and lesbians, as well as their supporters, marched the streets of Warsaw and received more applause and cheers from the general public than insults or anti-slogans from counter-demonstrators. The spirit of change is becoming more and more visible in today's Poland. Coming Out Polish Style features several characters who share their intimate experiences of 'coming out' as gays or lesbians and of the dramas and joys involved in the process of becoming true to oneself and finding integrity in the world.

From internationally-acclaimed director Lu Chuan, an epic story of war, of dreams fulfilled and of betrayals - betrayals of friendship, of ideals, and of oneself. Yu is a young noble: handsome, brave, admired. Commander of the era's most powerful army, he leads the revolt against the cruel Qin dynasty. Yu recognizes great potential in Liu, a peasant, and gives him command of 5,000 soldiers. Liu breaks an agreement with Yu by entering and ransacking the Qin capital alone. The Qin dynasty falls and Yu rules. Wary of treachery, his advisers plot to kill Liu at a great banquet, but the emperor spares his life. From this 'last supper', Liu will wage war against Yu. Xin, an adviser to Yu, joins him. Defeated, Yu commits suicide on the battlefield rather than submit to capture. Yu is dead, but now Xin is a threat. Liu imprisons then releases him, but broods about having spared Xin's life as Yu spared his... Xin too must die. Emperor Liu has finally reached his goal. But his soul remains deeply troubled - haunted by the ghosts of his betrayals, unable to find peace in the position he dreamed of and fought ruthlessly to achieve.

Christina Ricci stars in director Sarah Spillane's inspirational drama, a world premiere at the 2013 Toronto Film Festival. With encouragement from a drama teacher (Christina Ricci), a teen in Sydney, Australia (Hunter Page-Lochard) confronts his past and eventually takes control of his future. AROUND THE BLOCK is about breaking cycles and building dreams. Set in a contemporary, tough, inner-city precinct, this is a story of revenge and triumph, as a teenage boy is torn between his unexpected love of theatre and the disintegration of his family. With encouragement from his unconventional American drama teacher, he confronts his past and eventually takes control of his future.