The path to decarbonization

Is Canada on track to phase out coal by 2030?

Activity Image
40 mins
Group work


Using data about the consumption of electricity, students use mathematical concepts to develop conjectures about Canada’s ability to reach decarbonization goals and phase out coal by 2030.


What you'll need

  • "Thinking before and after" worksheet, one for each student
  • "Coal phase out" slides
  • Digital projector and screen

  1. Organize your students into pairs and provide each student with a copy of the "Thinking before and after" worksheet. 
  2. Open up the "Coal phase out" slides and display slide 2. Briefly explain that in 2018, the Government of Canada committed to phasing out coal-fired electricity generation by 2030. Invite groups to examine the graph and ask, “Is Canada on track to phase out coal by 2030? Absolutely, perhaps, or not possible?” Invite groups to share their decision and thinking with the class.
  3. Guide your students’ attention to the list of mathematical vocabulary on the worksheet. Show slide 3, then invite groups to describe the graph correctly using as many of the terms as possible.
  4. After groups have shared their descriptions with the class, invite them to offer a conjecture on the question “Is Canada on track to phase out coal by 2030? Absolutely, perhaps, or not possible?” Prompt groups to note their initial decisions at the bottom of the worksheet.  
  5. Encourage groups to share their conjectures with the class, reminding them to correctly use as many of the terms as possible in their explanations. 
  6. Invite groups to suggest what the graph would look like if coal was on track to be phased out by 2030. Gently remind your students to use the correct mathematical vocabulary to describe the features of the graph. 
  7. Explain that the challenge of this activity is to develop an accurate prediction of when Canada might phase out the use of coal-fired electricity generation.
  8. Ask groups to consider only the data from years 1997 onwards. Encourage students to use a line of best fit using these data points, then determine the x-intercept and/or equation of the line to approximate the year when electricity consumption generated by coal would fall to zero terawatt hours. 
  9. Display slide 4, and invite groups to compare their line of best fit and x-intercept to the one on the slide.
  10. Ask groups to revisit their last conjectures to draw a final conclusion on Canada’s progress towards phasing out coal. Encourage students to select the most useful mathematical information from the graphs to support their conclusion, reminding them to use mathematical vocabulary in their explanations.
  11. Invite students to revisit their initial conjectures on Canada’s progress towards decarbonization by phasing out coal. Encourage students to note their reflections on their decisions, reminding them to use mathematical vocabulary in their explanations. 

Curriculum Fit

Grade 9 Mathematics

Big idea

  • Continuous linear relationships can be identified and represented in many connected ways to identify regularities and make generalizations.


  • Two-variable linear relations, using graphing, interpolation, and extrapolation

Curricular competencies

Reasoning and analyzing
  • Use reasoning and logic to explore, analyze, and apply mathematical ideas
  • Estimate reasonably
Understanding and solving
  • Apply multiple strategies to solve problems in both abstract and contextualized situations
  • Develop, demonstrate, and apply mathematical understanding through play, inquiry, and problem solving
Communicating and representing
  • Use mathematical vocabulary and language to contribute to mathematical discussions
  • Explain and justify mathematical ideas and decisions
  • Communicate mathematical thinking in many ways
Connecting and reflecting
  • Reflect on mathematical thinking
  • Connect mathematical concepts to each other and to other areas and personal interests
  • Use mathematical arguments to support personal choices

Teaching Notes

  • Using the data provided in the sources, the consumption of coal-fired electricity will be zero terawatt-hours at (70.676, 0) or August, 2035.  


Assess your students’ abilities to:

  • Use mathematical vocabulary and language to contribute to mathematical discussions (e.g., increasing, decreasing, domain, range, slope, steepness, ordered pairs, clusters, linear regression, and x-intercept).

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