384 Investigating Diagonals 1

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Teacher Notes


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Activity OutcomeIdentifying the pattern of diagonals in polygons. (Patterns)
MTS Set MTS6
NATIONAL Curriculum Geometric Reasoning
Topics 2D Shape
Reason Geometrically
Keywords Pattern, 2D Shape
GroupingWhole class, small groups and independent.
ResourcesCopy the activity to an overhead sheet, an overhead projector.
Lesson Notes
  • Direct students to the Investigation and ask: What do we need to find out? Provide students with the opportunity to work in small groups to understand the question.
  • Bring groups together and ask: (Reflection) What do we need to find out?
  • Direct students to the Strategy and ask: How can we check for a rule? What are the steps we should take? Provide students with the opportunity to work in small groups to understand the Strategy steps.
  • Bring groups together and ask: (Reflection) How can we check for a rule? What information do we need to collect? How will we collect it? How will we record it? What will we look for in the information we collect? (A pattern.)
  • Direct students to the Working and ask: What actions do we take to find, collect and record information? Provide students with the opportunity to work in small groups to understand the Working steps.
  • Bring groups together and ask: (Reflection) What actions do we take to find, collect and record information?
  • Direct students to the Finding and ask: What do we hope to find in the data we have collected? Why are we looking for a pattern? Can you see a pattern in the number of diagonals drawn inside polygons? Provide students with the opportunity to work in small groups to identify a solution to the question.
  • Bring groups together and ask: (Reflection) Can you see a pattern in the number of diagonals drawn inside polygons?
  • How does this pattern help us understand how many diagonals you could draw inside any polygon?
ReflectionsSee Lesson Notes.
Internet Links
AnswersThe number of diagonals from one vertex in a polygon is equal to the number of sides in the polygon - 3.