Open the sports page of a newspaper, and find a box score. Discuss with the students the meaning of statistics. Break down each of the abbreviations in the box, so students understand each the statistics in each section.
Ask the students to calculate more statistics using the numbers in the box score. For baseball, have students calculate a player's batting average. Divide the hits by the number of times a player is at bat. Calculate the on-base percentage by adding the number of hits and walks with the number of times hit by a pitch, and dividing that number by the sum of the player's hits, walks, times hit by a pitch and sacrifice flies.
Look at other percentages that can be calculated using sports statistics. Find different sports throughout the year to make the math a little different.
Draft a fantasy basketball, football or baseball team as a class. Look at the players' statistical track records and different salary-cap values to choose the right players for the team.
Look at the statistics for the starting players once or twice a week, depending on how often the players play. Look at how many points one player scores compared to another using the game statistics or calculate other statistics using the statistics you have.
Follow the team throughout the season, increasing the difficulty of the math questions, and incorporating multiplication, addition, subtraction, division, fractions and algebra as appropriate. Change the teams each season, using different statistics to help develop the students' mathematics skills.