Grade 8: Number

Warm up with a few quick number warm-ups on the board while the class settles, so every child starts thinking about the skill.

This unit applies percentage skills to real financial contexts: simple interest on an investment or loan, discounted sale prices, and tax (GST) added to a price, each following its own two-step calculate-then-adjust pattern. Model the method clearly, thinking aloud:

• Introduce simple interest with the formula I = PRT/100, working through what each letter represents with a real example.
• Teach discount as: find the discount amount first, then subtract from the original price to get the sale price.
• Teach tax the same way but adding instead of subtracting, so students see the shared underlying pattern.
• Use realistic numbers (bank interest rates, common retail discounts, Australia's 10% GST) so the context feels real.
• Review the model: does the answer make sense given the original amount and the percentage involved?

Work this through step by step on the board, then have the class talk you through a second one.

• Find the simple interest on $2,000 invested at 5% per year for 3 years
• I = P x R x T / 100 = 2000 x 5 x 3 / 100 = $300

Do the first few questions of the practice worksheet together, one child explaining each step. Check for understanding before releasing the class to work alone.

Students complete the practice worksheet independently while you circulate and support.

Circulate and look for these, they are the usual sticking points:

• Forgetting to divide by 100 when using the simple interest formula or a percentage calculation.
• Using the wrong time period (e.g. months instead of years) without converting first.
• Subtracting a discount when a tax should be added, or vice versa.
• Calculating a percentage of the wrong amount (e.g. finding tax on the discounted price without being asked to).

Pull the class back together. Ask one child to explain number in their own words, pose a single check question everyone answers on a mini whiteboard, and name what you will build on next lesson.

Use the independent worksheet as the evidence. A child who can complete it accurately and explain one answer has met the objective; anyone who cannot needs the easier level and a short reteach next session.