For this FACTivity, you will answer the question: What is the difference between having a 50 percent chance of having something happen and having less or more than a 50 percent chance? You will answer this question by simulating shrimp moving downstream and potentially being caught by a pipe. Materials: 3 yardsticks 1 piece of 22-by-28-inch posterboard 100 marbles A coffee can Data log ( included ) Topics: Water, Wildlife, Experiment, Hands-on, Modeling, Rivers and Streams, Sampling, Shrimp.