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Lesson 1 of 3 · 45 minutes · Grade 12 (also Grade 11)

Bond repayment worksheet and lesson plan for Grade 12 Maths Literacy

  • 45-minute lesson plan
  • One-page printable worksheet
  • Answer key
  • Free, no sign-up

Part of Counter That for teachers, by Privately. Updated 9 October 2026. Every worked figure and answer on this page is computed from the game’s own engine, not typed.

Students see how the prime rate has moved since 2008, work out what one percentage point on prime does to the monthly repayment on a R1 000 000 bond, and test their instinct with the game's Rate Day guess. A bond that costs R10 152 a month at today's prime of 10.75% costs R10 837 after one more point, and the lesson makes that visible in rand, not only in percentages.

For: Grade 12 Mathematical Literacy (Finance: loans and interest).

What students will be able to do

  • Read a table of prime rate moves and say which years saw the biggest rises and falls.
  • Work out the total repaid and the interest paid on a bond from a monthly repayment, and say what share of the loan the interest is.
  • Calculate what a change in prime does to a monthly repayment, in rand and as a percentage, and scale it to a bigger or smaller bond by proportion.
  • Use the bank's 30% of income rule of thumb to say whether a repayment still fits after a rise.
  • Make a guess before looking at the answer, and use the reveal to correct the instinct.

Before the lesson

  • Open the game once on your own device so you know what this week's run looks like. The title screen names the years it plays, and the market changes every Monday.
  • Print Worksheet 1 with its Print worksheet button below, one per student or pair, or show it on a screen.
  • Each pair needs a phone, tablet or computer with a browser. There is nothing to install and no sign-up.

The lesson plan, minute by minute

  1. 5 min

    Guess first

    Hand out the worksheet. Students do part A without a calculator and without looking at the table. Take a show of hands for each band but do not reveal the answer yet.

  2. 20 min

    Play to the first Rate Day guess

    In pairs, open the game, keep Quick run selected, choose any character (Ayanda is the simplest, because she has no bond) and press Play now. A year opens with Rate Day (the year's average prime and what the Reserve Bank did) in the first year and in any year when prime moved. From the second year on, Rate Day asks for a guess first: four bands for how much a monthly repayment changes, with Skip always available and no penalty. A character with no variable bond is given the same R1 000 000, 20 year bond used on this worksheet. Students close the How to play card with Continue, end the year until a Rate Day with a guess comes up, pick a band, read the reveal, and fill in part C. If prime holds still in the early years of this week's run, they play on one more year, or choose the Full run.

  3. 15 min

    Work through the table

    Students complete part B with a calculator. Walk the room for question 1.4: the proportion step (a bond 1.8 times as big costs 1.8 times as much more) is where students are most likely to slip.

  4. 5 min

    Reveal and discuss

    Reveal the band from part A, compare it with the hands raised, then use the discussion prompt below.

Open Counter ThatQuick run, any character, Play now. No sign-up.

Worksheet 1 and answer key

The worksheet fits one A4 page. The answer key opens below it and prints only when you press its own button.

Counter That for teachers, by Privately

Worksheet 1: Interest rates and bond repayments

Mathematical Literacy, Finance: loans. Use a basic calculator.

A. Guess first (no calculator, no table yet)

  • Prime rises by 1 percentage point. About how much more will the monthly repayment be on a R1 000 000 bond over 20 years? Circle one.

    • Less than R250
    • R250 to R500
    • R500 to R750
    • More than R750

B. Prime rates and repayments

The left table gives prime at the start and the end of each year, as Counter That records it. The right table gives the monthly repayment on a R1 000 000 bond over 20 years (240 monthly repayments) at four prime rates, rounded to the rand.

Prime rate, start and end of year
YearStartEndChange (points)
200814.50%15.00%+0.50
200915.00%10.50%-4.50
20138.50%8.50%0.00
202010.00%7.00%-3.00
20217.00%7.25%+0.25
20227.25%10.50%+3.25
202310.50%11.75%+1.25
202511.25%10.25%-1.00
Monthly repayment on a R1 000 000 bond over 20 years
Prime rateMonthly repayment
7.25% (prime before the 2022 rises)R7 904
10.50% (prime after the 2022 rises)R9 984
10.75% (prime today)R10 152
11.75% (prime today plus 1 point)R10 837
  • 1.1

    In which year in the table did prime rise the most, and by how many percentage points? In which year did it fall the most, and by how many?

  • 1.2

    At today's prime, work out the total repaid over 20 years and the interest paid. What percentage of the amount borrowed is the interest?

  • 1.3

    Prime rose from 7.25% to 10.50% in 2022. By how much did the monthly repayment rise, in rand and as a percentage of the old repayment?

  • 1.4

    Use the table to find what one extra point on prime adds each month. How much would it add each month on a R1 800 000 bond? What is the extra over one year on the R1 000 000 bond?

  • 1.5

    A common bank rule is that the repayment should not be more than 30% of gross monthly income. A household earns R34 000 a month. What is the most it can repay? Does today's repayment fit? Does it still fit after one more point on prime? Say by how much.

C. From the game: your first Rate Day guess

  • Year: ______
  • Prime moved from ______ to ______
  • I guessed: ______________
  • The game said: ______________ a month
  • Right band? Yes / No

Figures: prime 10.75% (checked 24 September 2026), 2026/27 tax and transfer rules (checked 28 September 2026). Teaching examples, not quotes.

Answer key for teachers: Worksheet 1: Interest rates and bond repayments

Answer key, for teachers only

Answer key for worksheet 1: Interest rates and bond repayments

Every answer is computed from the game's engine. Where a printed figure is rounded to the rand, the answer is worked from the printed figure, and the unrounded figure is given beside it so a teacher can see the gap is only rounding.

A. The right band is R500 to R750. One extra point adds R685 a month.

  • R10 837 (prime 11.75%) less R10 152 (prime 10.75%) = R685.
  • The game states the same rule of thumb for this bond, about R685 a month for one point, on the first Rate Day for a player who has no bond of their own to apply it to.

1.1. Largest rise: 2022, up 3.25 points (7.25% to 10.50%). Largest fall: 2009, down 4.5 points (15.00% to 10.50%).

  • Read the Change column: the largest positive and the largest negative figure.

1.2. Total repaid R2 436 480. Interest paid R1 436 480, which is 143.6% of the amount borrowed.

  • Total repaid: 240 x R10 152 = R2 436 480.
  • Interest paid: R2 436 480 less R1 000 000 = R1 436 480.
  • As a share of the loan: R1 436 480 / R1 000 000 = 143.6%.
  • With the unrounded repayment a bank would quote, the interest is R1 436 549. The gap of R69 is only rounding.

1.3. The repayment rose by R2 080 a month, which is 26.3% more.

  • R9 984 less R7 904 = R2 080.
  • Percentage increase: R2 080 / R7 904 = 26.3%.

1.4. R685 a month on the R1 000 000 bond; about R1 233 a month on the R1 800 000 bond; R8 220 over one year on the R1 000 000 bond.

  • One point: R10 837 less R10 152 = R685.
  • A bond of R1 800 000 is 1.8 times as big, so the extra is 1.8 x R685 = R1 233 (unrounded R1 233).
  • One year: 12 x R685 = R8 220.

1.5. The most it can repay is R10 200. Today's repayment of R10 152 fits, with R48 to spare. After one more point it is R10 837, which is R637 over the limit and does not fit.

  • 30% of R34 000 = R10 200.
  • R10 200 less R10 152 = R48.
  • R10 837 less R10 200 = R637.

C. Marked against the game's own reveal. The game shows the right band after the guess, so students can check themselves.

  • A right band is a good sign but a wrong one is not a failure: the guess exists so the reveal sticks.
  • The game keeps a tally of right bands on that device only and sends nothing about it.

All repayments are rounded to the rand as printed, 240 months at prime 10.75% and the other three rates. The bank's own figure can differ by a few rand.

The Counter That quick run uses a different start year every Monday, so the Rate Day a student sees may be a different year from the one in the table. The table is for the paper exercise.

Discussion prompt

Prime rose 3.25 points in 2022, and the same R1 000 000 bond cost R2 080 more a month. A household that was comfortable before is not afterwards. What could it have done before the rises, and what could it do after? What would each choice cost?

Points to draw out

  • A cash buffer. The game measures it in months of outgoings, and a household with no buffer has no time to react.
  • Paying extra into the bond. It lowers the interest over the life of the loan, which is the CAPS question about how a change in the monthly repayment changes the real cost of a loan.
  • A fixed rate for a period. It removes the risk of a rise while it lasts, but in the game the banks price a fixed rate above the variable rate, and a fixed rate also stops the household gaining when rates fall.
  • A smaller bond or a bigger deposit. Both cut the repayment in proportion, as question 1.4 shows.
  • A longer term. It lowers the repayment and raises the total interest. Students can test this on a bank's online bond calculator or on the Privately calculator.
  • Make clear these are facts to weigh, not advice for any one household.

Curriculum link

Practises the CAPS Finance content on loans and interest in Grade 12 (house loans repaid monthly, and the effect of a change in the interest rate on the cost of a loan), with the real cost of a loan in Grades 11 and 12.

  • Grade 12 · Finance, Banking, loans and investments · page 56

    Loans from banks with a monthly repayment, house loans among the examples.

  • Grade 12 · Finance, Banking, loans and investments · page 57

    Investigate the effect of a change in the interest rate on the cost of a loan, and the effect of a change in the monthly repayment on the real cost of a loan.

  • Grades 11 and 12 · Finance, Banking, loans and investments · page 56

    Work out the real cost of a loan and the interest paid on it, using pen, paper, a basic calculator, tables, spreadsheets or a loan calculator such as the ones on bank websites.

  • Grade 12 · Finance, Interest · page 54

    Loans, including house loans, where a repayment is made every month.

  • Grade 10 · Finance, Interest · page 54

    Tell an interest rate from the interest it produces. Useful revision before Grade 12.

The CAPS says learners are not expected to know complex financial formulae and should work from tables and calculators, so the worksheet gives the monthly repayments and asks for the reasoning, never the repayment formula. The prime rate history table and the game's Rate Day guess are extras: the CAPS names no particular data set.

Page numbers are those printed in the Curriculum and Assessment Policy Statement (CAPS), Mathematical Literacy, Grades 10 to 12, 2011 edition, as published at education.gov.za. This is our own mapping: Privately is not affiliated with the Department of Basic Education and this lesson is not endorsed by it. Check it against your province’s annual teaching plan. Curriculum notes and sources.

Extension

Students check the table's repayments on the bond calculator, change the term from 20 to 25 years, and describe what happens to the repayment and to the total interest.

Questions about this lesson

What does one percentage point on prime cost on a bond?

On a R1 000 000 bond over 20 years, moving prime from 10.75% to 11.75% raises the monthly repayment from R10 152 to R10 837, which is R685 more a month. The cost scales with the size of the bond.

More free lesson plans

Counter That is an educational game with made-up homes, people and banks. The worksheets are teaching examples, not financial, legal or tax advice. No student data is collected: the privacy notes say what happens when a class plays.