MathStart 3: Safari Park (Finding Unknowns)

Grandpa's taking all the grandkids to the neatest amusement park ever: Safari Park. The Jungle King rides all cost 4 tickets. Rhino Rides are just two tickets. Monkey Games and Tiger Treats are a bargain at one ticket each. But a ride on the "spectacular, amazing, heart-pounding Terrible Tarantula" costs six tickets! Each of the kids has 20 tickets and has to figure out the best combination to have the most fun. What would you choose? An essential part of early algebraic thinking is understanding a "number sentence" with a missing element (8 + ? = 20), and the process for figuring out the unknown. Used with permission from Stuart J. Murphy.