Core Elective Investigating Problem Solving DrYeap Ban Har Marshall Cavendish Institute Singapore
1. Core Elective Investigating Problem Solving DrYeap Ban Har Marshall Cavendish Institute Singapore banhar@sg.marshallcavendish.com Sculpture: Riverside Merchants Singapore River www.marshallcavendish.com/education/mci
13. 27 x 5 = 150 – 15 = 135 135 ÷ 3 = 40 + 5 = 45 Each shelf had 45 books at first. National Singapore Math Summer Institute Denver, USA
14. Other methods offered by participants Algebraic Method 30x = 27(x + 5) Hence 30x = 27x + 27 x 5 30x – 27x = 135 3x = 135 x = 45 where x is the number of books on each shelf at first Model Method The bar model may look rather cumbersome with one bar of 30 units and an equal bar of 27 longer units. 5
15. Draw a polygon with 4 dots on the sides and find its area. National Singapore Math Summer Institute Denver, USA
16. Area Number of Dots National Singapore Math Summer Institute Denver, USA
17. There was a hypothesis by a participant that the area is also related to dots shown by arrows – dots that are “untouched” by the polygon when the smallest possible rectangle is drawn around the polygon. Can you figure this one out? National Singapore Math Summer Institute Denver, USA
18. Applying this hypothesis, the square has 4 “untouched” dots and the rhombus has 8 “untouched” dots National Singapore Math Summer Institute Denver, USA
20. High School Attached to Tsukuba University, Japan Draw a polygon with no dots inside it. Investigate. A polygon has 4 dots on the perimeter. Find an expression for its area. www.marshallcavendish.com/education/mci