Lesson plan

1. Understand that two half hours are the same as one hour (C)

teaches Common Core State Standards CCSS.Math.Content.1.MD.B.3 http://corestandards.org/Math/Content/1/MD/B/3
teaches Common Core State Standards CCSS.Math.Practice.MP6 http://corestandards.org/Math/Practice/MP6
teaches Common Core State Standards CCSS.Math.Practice.MP7 http://corestandards.org/Math/Practice/MP7
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Lesson objective: Understand that two half hours are the same as one hour.

Students bring prior knowledge of telling time from determining the hour on analog and digital clocks. This prior knowledge is extended to half hours as students determine what it means when the minute hand is on the six. A conceptual challenge students may encounter is that the analog clock shows a six, but the time is read as 30 minutes past the hour. 

The concept is developed through work with an analog clock divided into two halves, which shows students that the six actually represents the halfway point in the minute hand's rotation through one full hour.

This work helps students deepen their understanding of equivalence because it shows students that one hour is equivalent to two half hours in the same way that two semi-circles are equivalent to a whole circle.

Students engage in Mathematical Practice 7 (look for and make use of structure) as they extend their knowledge of hours on the analog clock to include half hours.

Key vocabulary:

  • Half hour
  • Half past
  • Minute hand