Mental Math

Prepared by Shari Davis and Katherine Smith as part of a series of supplemental critical thinking explorations to promote discovery and deeper comprehension.
This project was supported by a 2017 Faculty Innovator Grant through Old Dominion University’s Center for Learning and Teaching.

Part 1

Getting Ready

There is nothing students need to do to prepare for this exploration.

Video

Students should watch the following video: Critical Thinking Exploration 4 Part 1 Video

Follow-up

After watching the video, students should be given time explore finding multiples of 10% of a number. This could take place in class, after class or using an online discussion board.

A sample discussion board prompt would be: Take a few minutes to practice by finding:

  • 10% of 130
  • 60% of 50
  • 70% of 60

Part 2

Getting Ready

Students should have viewed Part 1 of this exploration and had time to complete the follow-up activity.

Video

Students should watch the following video: Critical Thinking Exploration 4 Part 2 Video

Follow-up

After watching the video, students should be given time explore finding percentages of a number ending where the percent ends in a 5 or 0. This could take place in class, after class or using an online discussion board.

A sample discussion board prompt would be: Take a few minutes to practice by finding:

  • 85% of 80
  • 25% of 50
  • 15% of 40