This is a problem solving activity for uniform probability. A situation is described where students will draw a graph of the density curve and calculate probabilities for a random variable from this graph. The students will develop their own understanding of how the probabilities are calculated from the area of the graph and how to calculate the height of the density curve. The shape of the density curve is a trapezoid to make the calculations for the area more of a challenge. The lesson plan is simply give them the handout and allow them to work in groups. The trouble spots are how to find the height of the density curve using algebra and an unknown for the height and knowing the total area of the trapezoid is equal to 1 for 100%. The solution strategies for calculating the area are to either use the equation for a trapezoid or the sum of a rectangle and a triangle. Then a class discussion at the end to make sure each student is on the right page and seeing others' solution strategies.