Getting third graders to think proportionally is a fantastic way to encourage modeling, and to “prime the pump” for proportional thinking when working with fractions. Simple proportional thinking can be so clearly seen with models that it is accessible to all students. There are so many real-world contexts relating to proportions that are near and dear to a third graders heart! Think about candy, carnival prizes, field trips and much more.
An added bonus – math work that lends itself to modeling and is easy to justify with a model. I asked students to examine a small bag of M & Ms. Based on the number of each color in the small bag, students needed to figure out how many of each color would be in a giant bag of M & Ms. Students were busy grabbing their colored pencils and large mat papers before we even answered the last “need more information question”.
Added, added bonus – many students were able to make a connection to multiples with this activity. Some students began to take shortcuts, which is just really using math in the most efficient way, by using ideas of multiples.