Someone in an online discussion posted a link
to what was claimed to be an experimental demonstration of global warming by a young student. It was presented by the Cleveland Museum of Natural History and the Clean Air Conservancy.
The experiment consisted of filling one jar with CO2 and one with ordinary air, illuminating both with heat lamps, and observing the temperature. The temperature in the jar with CO2 went up more. The experimental design was imperfect, since the lamps might have differed a little in intensity or placement, but that's not a serious criticism given the age of the experimenter.
The real problem is that the experiment does not demonstrate the greenhouse effect. That effect depends on selective absorption, on the fact that CO2 is more transparent to the short wave length light coming down from the sun than to the long wave length light coming up from the Earth. The experiment showed that CO2 was less transparent than ordinary air to long wave length light but provided no evidence at all of its transparency to short wave length light, hence no evidence in support of the greenhouse effect. To do it right, it should have been repeated using a source of short wave length light such as sunlight. If that didn't heat the bottle with the CO2 more than the other bottle, that would have provided evidence of selective absorption, hence support for the claim that CO2 is a greenhouse gas.
My conclusion is that the people who webbed the video were ignorant of the science they claimed to be demonstrating. The student who did the experiment was equally ignorant, which suggests, but does not prove, that whoever taught him was as well. The case of the student or the Clean Air Conservancy isn't all that surprising, but it is a little disturbing that the Cleveland Museum of Natural History would post a video based on a complete misunderstanding of the science it purports to demonstrate.