Donald Trump has been calling out Joe Biden on his mental abilities lately. In a recent Fox News interview, Trump boasted about his scores on a cognitive test and challenged Biden to take the same test. Biden should turn the challenge around.
Biden should prepare a list of 100 questions that the President should know. The questions should not be tricky or hard. Examples are the names of leaders of important countries. Whether certain countries are in NATO or other alliances. Names of cabinet members and what their departments are responsible for. Questions about the US constitution. All questions that Biden and any other politician in Washington should know the answers to off-hand.
Biden should then send the questions to the news media. He should invite them to pick 3-5 random questions from the list to ask Trump the next time he has a news conference. See how many he gets right.
Most likely, when asked a question from the list, Trump will just try to change the subject.