Percentages from first principles (Year 8)


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“We have surveyed one hundred people and asked them the question….” I’m guessing all of you have watched Family Feud at least once and heard Grant Denyer read out all sorts of questions and received some surprising answers from the players. This game is based on percentages, which is our topic of study for the next week. There are a series of concepts you need to understand, with increasing levels of difficulty, listed below:

  •  I understand that percentage means “out of one hundred”. 30% means 30 out of every 100 or 3 out of every 10 or 0.3 out of 1.0
  • I can (always, usually, sometimes, never) convert between percentages, fractions and decimals. For example, 25% = 25/100 = 1/4 = 0.25
  • I can (always, usually, sometimes, never) calculate the percentage of an amount (with/without) using a calculator. For example, 15% 0f 300 = 15 x 3 = 45
  • I can (always, usually, sometimes, never) calculate a percentage discount, profit or loss. For example, a pair of $80 jeans were on sale with a 10% discount, what is the sale price? $80 – (10% of 80) = $80 – $8 = $72.00
  • I can (always, usually, sometimes, never) work out the percentage increase or decrease of two amounts. For example, the median house price rose from $150,000 to $175,000, so the percentage increase was (175,000 – 150,000)/150,000 = (about) 17%

Some resources:

  1. Introduction to Percentages (Maths is Fun)
  2. ABC Splash video – converting fractions to percentages
  3. BBC Bitesize – Percentages and BBC Bitesize – Finding Percentages
  4. A BBC activity about Percentages
  5. Solving problems with percentages from Math Planet (with two videos)
  6. ABC Splash video – How Banks make Money
  7. Five quick questions to test your percentages from Maths is Fun
  8. ABC Splash – Design a Farm

Percentages, Profit and Loss (Year 8)


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Learning Intentions: Solve problems involving profit and loss, and the use of percentages, including percentage increases and decreases, with and without digital technologies.

Whenever you buy something, the shop owner has to put a price on that item, usually so that he can make a profit. Food such as fruit and vegetables will usually have a smaller margin (percentage profit) than more expensive items such as clothing and appliances. In Australia, the “Goods and Services Tax” (GST) of 10% is applied to almost all consumer items, except fresh produce. So, if you pay $55.00 for an item, $50.00 is for the shopkeeper and $5.00 is the GST, which goes to the federal government tax office.

Fractions Apps on the iPad

Learning Intention: This lesson we will be using three different apps on the iPads to learn about the value of fractions, decimals and percentages.

Success Criteria: Students will understand the value of common fractions (1/2, 3/4, 1/3, 2/3 etc) and be able to order a list of common fractions, decimals and percentages.

1. Motion Math HD – Bounce the fraction ball at the corresponding point on the number line by moving the iPad (10 minutes).

2. Fraction Factory – Move the factory cog to the correct point on the number line (10 minutes).

3. Number Line – Order the fractions, decimals and percentages from smallest to largest (10 minutes).

Please leave a comment below about which app you liked best, why you liked it and what you learnt.