I think most 14 year olds (who attend school) would know that a drawing of an atoms nucleus comprised of little colored marbles is not really supposed to be an accurate description of a nucleus. Edited to add - my derogatory comments were about the author of the web site not Mr. Fresh.
I disagree. They should be told that it is a simplified model, but it would be sufficient for the needs of a 14 year old. You could even let them use a few wooden toothpicks and balls of coloured plasticine, for making molecules. Don't be such a spoilsport.