A tutorial that is not especially useful. It uses critical value rather than p-value, so I would not use it in my classes. It uses r for the number of successes rather than x. It does not explain very well what it is asking for. Students must be given a tutorial before using. For example, when it asked for "p", I thought it wanted me to solve for the z-value and get the p-value. Actually it was asking for the proportion for the sample. It uses "reject the null" rather than talking about "evidence of a significant ...". It does not indicate whether or not my answer is correct. I might have used this twenty years ago but in my class, this tutorial is out-of-date.