This is a great idea for a 2-3 minute warmup at the start of class. These are pictures from ads, articles, signs, etc. that contain some sort of math error. Some signs are humorous and others are just misleading. Students will enjoy finding math errors made by others. Does it really matter if you put the decimal point in the wrong place? Does spelling count when you are working with math? Are the advertised sales really bargains? Students can explore math concepts in a variety of contexts. This would be a great end of the year activity or a good intro at the beginning of the year.