This month’s curricular competency focus is using multiple strategies to solve problems. There is a development in how strategies are used from K-12 and for what types of problems.
In K-5 the curricular competency language is “develop and use multiple strategies to engage in problem solving” with elaborations including examples of strategies involving visual, oral and symbolic forms and through play and experimentation.
In K-5, we support students in developing a repertoire of strategies to draw upon and we encourage the practice of choosing and using these strategies in different problem solving experiences ranging from structured word/story problems, open problems or questions or problem-based or numeracy tasks. During the development of strategies, students will notice similar strategies being shared by their classmates and these strategies might be named such as “looking for a pattern” or “acting it out” or “represent with materials”. Naming strategies such as these helps to enhance mathematical communication, discourse and community in the classroom when discussing mathematical problems.
As with many of the curricular competencies in math, there are slight variations between grade bands, showing the developing application and demonstration of these competencies.
In grades 6-9 the curricular competency language is “apply multiple strategies to solve problems in both abstract and contextualized situations” with elaborations including examples of strategies focusing on those that are familiar, personal or from other cultures. Students in this grade range are refining and reflecting on their own use of problem solving strategies and we encourage students to listen and learn from their peers in order to consider new ways to think about a mathematics problem.
In grade 10 the curricular competency language is “apply flexible and strategic approaches to solve problems” with elaborations such as deciding what tools to use to solve a problem as choosing from a list of known strategies such as guess and check, solve a simpler problem, model, use a chart, role-play or use diagrams. The numeracy processes for engaging in numeracy tasks are related to this competency at the secondary level – interpret, apply, solve, analyze and communicate.
Although specific strategies such as “guess and check” or “solve a simpler problem” are not named specifically in the elaborations from K-9, it is these more formally named strategies that are developed with understanding, meaning and purpose over time. Alternative or personally derived or preferred strategies may also be developed by students and shared with their solutions, supported with their reasoning and explanations to demonstrate their understanding of the problem and the mathematics involved.
Many math educators and researchers have found over decades of research and classroom experiences that students who have multiple strategies or approaches to problems are more fluent and flexible in their thinking. An important aspect of using multiple strategies is knowing when a particularly strategy is helpful or efficient. Not all strategies are suitable for all problems and this an important part of the progression of developing this competency in mathematics One particularly effective instructional strategy is engaging students in comparing the strategies they used to solve a problem. Researchers have recently examined the cognitive process of comparison and how it supports learning in mathematics. The sharing and comparison of multiple student strategies for a problem was found to be particularly effective for developing procedural flexibility across students and to support conceptual and procedural knowledge for students with some background knowledge around one of the strategies compared. (Durkin et al, 2017 – referenced below). Based on their findings, the researchers share some significant instructional moves that will support student learning:
1) regular and frequent comparison of alternative strategies
2) judicious selection of strategies and problems to compare
3) carefully designed visual presentation of the multiple strategies
4) small group and whole class discussions around comparison of strategies with a focus on similarities, differences, affordances and constraints
Examples of what the use of multiple strategies might look like in the classroom include:
Primary: The teacher reads the story The Frog in the Bog and asks the grade 1 students to figure out how many critters are in the frog’s tummy. The teacher invites the students to think about how they might solve this problem and what they will need. The students work on their own or with a partner to solve the problem through building with materials, acting it out, drawing or recording with tally marks and numbers. Some students accompany their solutions with an equation and one student records his ideas orally using iPad technology. As the students are working, the teacher pauses the students and asks them to walk around the room and see what their classmates are doing and see if they can find a new idea for their own work. After solving the problem, the students prepare to share their solutions and strategies with the class and the teacher gathers the students on the carpet and chooses some students who used different strategies to share. The teacher records the strategies on the chart and then asks the students if they have a new idea for a strategy for the next time they do a problem like this.
Intermediate: In a grades 6&7 class, the teacher projects the first three figures of a visual pattern on the class whiteboard (examples on visual patterns.org). The teacher asks the students what they notice about the figures and records some of the students’ responses and then asks them to consider what comes next. Students are asked to consider what strategies or approaches might help them think about this. After some thinking time, the teacher asks the students to turn and talk with one or two other students and compare each others’ strategies and consider new ways of thinking about the problem. The teacher then invites the students to apply more than one strategy to solve what figure 43 will look like. The students share their solutions and strategies with the teacher recording the different strategies through different representations such as a drawing, a narrative, an expression, a table or a graph. The teacher then facilitates a discussion comparing the representations and how they are connected and support the understanding of the problem.
(with thanks to Fawn Nguyen and Marc Garneau for the inspiration)
Secondary: Students in a grade 10 class are assigned to be in random groups of three and work on a numeracy task on a whiteboard or window around the classroom. The class has been learning about prime factorization and the teacher shares the following problem orally:
Prime numbers have exactly two factors – 1 and itself. Which numbers have exactly 3 factors? Exactly 4 factors? And so on. Given any positive integer, n, how can you tell exactly how many factors it has?
Each group of students begins talking and sharing their ideas. Students begin to record their thinking, using diagrams, charts, numbers, etc. and build on and challenge each others’ thinking about the problem and approaches to solving it. Students move around the room and watch or engage with other groups. The teacher facilitates students’ sharing of solutions and approaches to the problem and then provides a set of related problems for students to continue practicing with, either in their groups or independently.
(with thanks to Mike Pruner and Dr. Peter Liljedahl for the thinking classroom inspiration)
Some questions to consider as you plan for learning opportunities to develop the competency of using multiple strategies and approaches to solve problems:
What strategies and approaches do you notice your students using? Are some students “stuck” using the same strategy? How could you nudge students to try different strategies and approaches?
What different types and structures of math problems are being provided to your students? Are students flexible with their strategy choice or approach, making decisions based on the problem they are working on?
How might you and your students record their strategies and approaches to make this thinking visible?
What opportunities are we creating for students to watch and listen to others think through, choose and apply strategies and solve problems? How might this support their learning?
What tools, materials and resources do students have access to to support choice and application of different strategies and approaches when solving math problems?
Elementary and Middle School Mathematics: Teaching Developmentally by John van de Walle et al
Teaching Mathematics through Problem-Solving (NCTM) edited by Frank Lester and Randall Charles
Durkin, K., Star, Jon. R. & Rittle-Johnson, B. (2017) Using Comparison of Multiple Strategies in the Mathematics Classroom: Lessons Learned and Next Steps, ZDM: The International Journal on Matheamtics Education 49(4), 585-597.