Blackboard ‘chalk’ are produced especially for use with blackboards in white and also in various colours. White chalk sticks are made mainly from calcium carbonate derived from mineral chalk rock or limestone, while colored or pastel chalks are made from calcium sulfate in its dihydrate form, CaSO·2HO, derived from gypsum. Chalk sticks containing calcium carbonate typically contain 40–60% of CaCO (calcite). As compared to whiteboards, blackboards still have a variety of advantages: On the other hand, chalk produces dust, the amount depending on the quality of chalk used. Some people find this uncomfortable or may be allergic to it, and according
What Planet Are You From? critics, currently holding a 42% score on Rotten Tomatoes based on 77 reviews, with an average rating of 5/10. The site's consensus states: "Though "What Planet Are You From?" has some laughs, it's too inconsistent and bland for critics to give it their recommendations." Metacritic reports a 41 out of 100 rating based on 32 critics, indicating "mixed or average reviews". What Planet Are You From? What Planet Are You From? is a 2000 American science fiction comedy film directed by Mike Nichols and written by Michael Leeson, Garry Shandling, Ed Solomon, and Peter Tolan based on a story by