They created the number system and discovered that the earth was round by studying eclipses.
Hope this helps.
1. Jacob Riis. In the late 1800s, the rapid growth of cities during America's second wave of industrialization produced serious problems. Overcrowding in huge apartment buildings known as tenements were unsanitary, and garbage accumulated in the streets, leading to the spread of disease. Poverty was common, and crime was a result. Jacob Riis was a Danish immigrant who took photographs of the horrible living conditions in New York City. His photos in "How the Other Half Lives" shocked Americans and resulted in many reformers campaigning for better water and sewage systems and vaccinations.
2. NAACP. The NAACP, or the National Association for the Advancement of Colored People, was formed in 1909. In the late 1800s and early 1900s, African Americans in the North and South faced discrimination. Even though slavery had been abolished by the 13th amendment in 1865, African Americans were denied basic rights. Many notable African Americans from this time period advocated for full equality, such as Booker T. Washington, Ida B. Wells, and W.E.B. Dubois. Dubois believed that under no circumstances should African Americans accept segregation, and he helped found the NAACP to help with attempts to gain legal and economic equality for African Americans.
3. Conservation. The protection and preservation of natural resources is known as conservation. One of the most prominent leaders of the conservation movement was President Theodore Roosevelt. A progressive president and an avid outdoorsman, Roosevelt began to protect America's natural resources by establishing some of the first national parks for future generations. Other progressive presidents, such as William H. Taft and Woodrow Wilson, also contributed greatly to conservation efforts in the early 1900s.
4. Jim Crow Laws. After the abolition of slavery in 1865, laws in Southern states were put into place to separate blacks and whites. These laws were called "Jim Crow" laws, named after a character in a song. Jim Crow laws required the separation of African Americans and whites in nearly any public place they might come in contact with each other. A famous court case in 1896, Plessy v. Ferguson enforced the concept of "separate but equal" facilities and institutions to segregate blacks and whites.
<span>African Americans labored in a system that was nearly the same as slavery.</span>
