The following text is for question 76- 78

Text 1

    High school students may improve their science grades by learning about the personal struggles and failed experiments of great scientist such as Albert Einstein and Marie Curie.

    In one study, 402 students from New York City high schools in low-income areas of the Bronx and Harlem were divided into three groups. The control group read an 800-word typical science and textbook description about the great accomplishments of Einstein, Curie and Michael Faraday.

  Another group read about those scientists' personal struggles, including Einstein's flight from Nazi Germany to avoid persecution as a Jew. The third group of students read about the scientists' intellectual struggles, such as Curie's persistence despite a string of failed experiments. The struggle stories included actions the scientist took to overcome these hurdles.

   Students who read about the scientist' intellectual or personal struggles were more likely to say the famous scientist were people, li ke themselves, who had to overcome failure and obstacles to succeed. Students in the control group more often believed the great scientist had innate talent and a special aptitude for science.

    The study suggests that science textbooks should highlight the struggles of great scientists and provide more vivid narrative descriptions of the techniques that scientists used to overcome challenges. "Many kids do not see science as part of their everyday lives. We teach them important content, but we never bring it to life;' sa id the lead researcher Xiaodong Lin-Siegler. PhD. "Our science curriculum is impersonal, and kids have a hard time relating to it because they just see a long list of fact that they have to memorize."

Adapted from:http://www.tc.columbia.edu/articles/2016/february/learning-about-struggles-of-famous-scientists-may-help-students-succeed-in-scie/)

The word Hurdles (paragraph 3, line 19) in the passage means ____.