In the latest example of bias against conservatives, YouTube is censoring videos from conservative group PragerU by placing them on "restricted mode."

The category, which is applied to videos that may contain " potentially objectionable content," was applied to 21 PragerU videos, the group announced on its Facebook page on Tuesday.

The group has created a petition to get YouTube to stop the censorship, and has already received more than 20,000 signatures. The 21 videos account for 10 percent of PragerU's video collection, and include videos asking: "Are the Police Racist?" "Are 1 in 5 Women Raped at College?" and "Is America Racist?"

PragerU, or Prager University, is the brainchild of radio host Dennis Prager, and offers short, five-minute videos about a range of topics presented from a Judeo-Christian and conservative perspective. The videos use slick graphics and statistics to summarize complex issues such as racism and foreign policy.

Jared Sichel, communications director for PragerU, said in a statement that the organization has been communicating with YouTube, which is owned by Google, for "several months" trying to get their videos uncensored. Sichel explained what placing the videos in "restricted mode" does.

"Restricted mode is something that many parents and schools use so that children don't watch explicit adult and sexual content — not so they can't find animated, educational videos on topics ranging from history and economics to happiness and philosophy," he wrote.

Because YouTube and Google has refused to relent, Sichel said, the organization started the petition. Another spokesperson for the organization told the Washington Examiner that news reports generated Tuesday about the petition have so far not resulted in the videos becoming uncensored.

For comparison, PragerU posted to its Facebook page that videos addressing similar topics from the liberal Vox are not placed in restricted mode. For instance, the PragerU video "Is America Racist?" is in restricted mode, while Vox's "The racist history of US immigration history" is not.

In a press release about the censored videos, Sichel wrote: "There is no excuse for Google and YouTube censoring and restricting any PragerU videos, which are produced with the sole intent of education people of all ages about America's founding values."

There is nothing explicitly adult or sexual about the PragerU videos, at least no more than any Vox video. It seems simply to be yet another example of bias against conservative ideas and inconvenient facts that contradict the liberal narrative.

Ashe Schow is a commentary writer for the Washington Examiner.