Raising the Money

The problem asks students to interpret a cumulative total on a linear scale. This is the same as reading a thermometer or finding the distance between numbers on a number line.
Some students may need help to read the scale. An essential principle of scale is that a linear measure has been reduced or, in some cases, enlarged. Due to this shrinking, not all unit marks can be shown on the scale. In this fund-raising scale, the marks shown represent differences of $200. Students will need to read up or down from the nearest $1,000 mark and subtract each previous total from the new total to work out how much money was raised during each event.
You could ask supplementary questions about the fund-raising activities. For example:
“How many cars did they wash? How much did they charge for each car? How much did the sponges, buckets, shampoo, and other materials cost?”
“How many bins of apples do you think the students picked? How long would they have picked for to fill that many bins?”
“What would you charge students at your school to get into a disco? How many students do you think went to the disco at Te Kauri School?”
For question 2, encourage students to estimate the solution first. They will need to understand that only the 30 students will pay the remaining $800, not the adults. Expect students to give answers like:
“If there were $600 to raise, that would be $20 each, and if there were $900 to raise, that would be $30 each. So the answer must be closer to $30 than $20, say $27.”
Although an absolutely accurate answer is 800 ÷ 30 = 26.6, this is not an actual monetary amount. The closest cash amount possible is $26.70, although $26.67 could be paid by cheque or Eftpos.

Answers to Activity

1. a. $1,200
b. $800
c. $600
d. $800
e. $400
f. $400
2. $26.67 each if paid by cheque or Eftpos, or $26.70 in cash