March · Month 7 of the money year

Interest

“Why does money grow for savers — and cost more for borrowers?”

By the end of the month, pupils can build 1%, 5% and 10% from a hundred-grid, describe the interest a saver may earn and the extra a borrower pays, explain compounding over two rounds, and ask fair questions about an interest claim.

Ages 8–11 · 4 lessons + a mission · 45 min each

🖨️ Print the pupil workbook Browse in the Lesson Finder

📖 Also in the printable year workbook (PDF), pupil pp. 95–109

The month's teaching plan

Four 45-minute lessons in this order, then the classroom mission.

Five in every hundred

Goldie · 45 min

Goal: Build 1%, 5% and 10% from a hundred grid before using a percentage to find a small interest amount.

percentagehundredrateamount

You need: one hundred-square grid per pair, ten counters, fictional €100 and €20 saver cards.

Lesson plan (45 min) + what pupils do+

Scenario

Shade 5 of 100 squares. On fictional saver cards, find 5% of €100 and 5% of €20. The rate is the same, but is the euro amount the same?

45-minute flow

5m ask what “5 in every 100” might look like; 8m shade 5 of 100 squares and show 10% as ten squares, then 1% as one; 20m pairs build 5% of €100 and 10% of €20 with counters, explain why both are €5 and €2 respectively, and check 5% of €20 as half of 10%; 8m compare rate (the percentage) with amount (the euro result); 4m exit: point to 5% on a grid and name 5% of €100.

What pupils do

Shade 5 squares out of 100. What percentage is shaded?
On a fictional €100 balance, what is 5% in euros?
If 10% of €20 is €2, what is 5% of €20?
Is “5%” the same thing as “€5” for every starting balance? Explain.

Interest for a saver

Goldie · 45 min

Goal: Describe interest as an amount an account may add under its terms.

interestratebalanceterm

You need: fictional one-year savings card: €100 starting balance, 5% annual rate, no deposits, no fees.

Lesson plan (45 min) + what pupils do+

Scenario

This fictional card says: start with €100, earn 5% once after one year, make no new deposits and pay no fees. Find the amount added and the closing balance. Compare €20 under the same rule.

45-minute flow

5m ask whether €100 could change while untouched; 8m model 5% of €100 as €5; 20m pairs solve €20 at 5% and €100 at 2% with hundred grids; 8m discuss that real rates can change and inflation affects buying power; 4m exit: who receives the interest in this example?

What pupils do

On the stated €100 card, calculate one year's interest.
Closing balance?
€20 at 5% for one year gives how much interest?
Is 5% promised forever? Explain.

Interest for a borrower

Goldie · 45 min

Goal: Calculate a simple total repayment and recognise that fees or timing can change actual costs.

borrowprincipalinteresttotal repayment

You need: fictional one-year loan card: borrow €100, pay €5 interest once, no other fees.

Lesson plan (45 min) + what pupils do+

Scenario

Card 1: borrow €100 and repay €105 after one year, with no other fee. Card A: borrow €20 and repay €22. Card B: borrow €20 and repay €25. Name the extra cost on each card.

45-minute flow

5m ask whether receiving €100 today means owning it; 8m model repay €100+€5; 20m groups compare card A (borrow €20, repay €22) and card B (borrow €20, repay €25); 8m discuss total repayment rather than just “small weekly payment”; 4m exit: who pays interest here?

What pupils do

Total repayment for the €100 card?
Cost of borrowing on A and B?
Which costs less if all other terms are the same?
Why would an adult need the full agreement, not only the weekly amount?

Growth on growth

Goldie · 45 min

Goal: Explain compounding through two rounds and distinguish a smooth model from a real investment path.

compoundreturnuncertaintyillustration

You need: fictional model: €100 grows 10% in each of two rounds; calculator optional.

Lesson plan (45 min) + what pupils do+

Scenario

The fictional model starts at €100 and adds 10% after each round. Round two uses the new balance from round one. Compare with a model that adds €10 each round. Neither model predicts a real investment.

45-minute flow

5m predict the second round; 8m model round 1: €100→€110, round 2: 10% of €110 is €11; 20m groups compare compound €121 with simple €120, then draw an uneven alternative path; 8m discuss why a return is not guaranteed and losses are possible; 4m exit: define growth on growth.

What pupils do

Fill round 1 and round 2 balances.
Why is round 2 growth €11 rather than €10?
Compare €121 and €120.
Correct the claim “It will always grow 10% each year.”

Final mission

Read the whole claim

Goldie · 45 min · independent, after rehearsal

Goal: Ask evidence-based questions about an interest claim, identifying missing term, fees and uncertainty before calculating.

Lesson plan (45 min) + what pupils do+

Scenario

Fictional poster A states “€100 grows 5% in one year, no fee.” Fictional poster B states only “Earn more! 8%!” Find A's result. Mark the missing starting balance, term and fee information on B; do not invent its ending balance.

45-minute flow

5m show poster B and invite a first reaction; 8m model questions about starting balance, term, fees and whether the number is a promise; 20m groups calculate A's stated €105 ending balance, mark B's missing information, and rewrite B as a question list rather than inventing an answer; 8m compare a justified calculation with an unsupported guess; 4m exit: name one fact required before using B.

What pupils do

Under A's stated rules, what is 5% of €100 and the ending balance?
Circle the facts missing from B: term, fees, starting balance, colour of the poster.
Can you calculate B's exact ending balance from the information given? Why?
Write one question you would ask a trusted adult before accepting a money claim.

Optional extensions

Extra lessons for classes that move faster — invitations, not compulsory homework.

Same rate, different starting amount

Goldie · 45 min

Compare interest amounts fairly when starting balances differ, without confusing a larger euro gain with a higher rate.

One year or two?

Goldie · 45 min

Read the term of a simple-interest classroom card and calculate repeated fixed interest without silently compounding.

The fee changes the result

Goldie · 45 min

Distinguish interest earned from the final balance after a stated fee.

More euros, fewer choices?

Goldie · 45 min

Explain with a concrete fictional basket why a higher money balance does not always buy more things when prices also change.

Practise it — free games & tools

The same ideas as a game or tool a child does themselves — for a station, quiet time or home.

Compound Magic Compound Growth tool Index Time Machine

For the teacher

Prepare once

Print the hundred-grid and interest-card pages, and a few fictional saver cards ('adds 5% a year') and borrower cards ('pay back €10 plus €1'). Use a board for the two-round compounding model. All rates are fictional classroom examples, not real products.

Adapt for your class

For 6–8, build 10% and 5% on the hundred-grid and read amounts — no formula. For 9–12, calculate a second round of compounding and compare two starting amounts at the same rate. Offer the hundred-grid as a counting scaffold and keep amounts in whole euros.

Assess the mission

In the mission (read the whole claim), mark: a percentage is built or applied correctly; the missing information in a claim is named; and the pupil separates 'interest earned' from 'final balance after a fee'. Being a careful reader of a claim is the real win — this is education, not advice.

The pupil workbook

Print-ready A4 pages: cover, diagnostic, every lesson with writing space, the mission, reflection and cut-out coins. Open and print (or save as PDF).

Open the workbook →

Next month: April — Investing

Education only — not financial advice. All shops, prices and people in the scenarios are fictional.

Interest

“Why does money grow for savers — and cost more for borrowers?”

Ages 8–11 · 4 lessons + a mission · 45 min each

📖 Also in the printable year workbook (PDF), pupil pp. 95–109

📈 Interest

The month's teaching plan

Five in every hundred

Interest for a saver

Interest for a borrower

Growth on growth

Read the whole claim

Optional extensions

Same rate, different starting amount

One year or two?

The fee changes the result

More euros, fewer choices?

Practise it — free games & tools

For the teacher

Prepare once

Adapt for your class

Assess the mission

The pupil workbook

📈 Interest

The month's teaching plan

Five in every hundred

Interest for a saver

Interest for a borrower

Growth on growth

Read the whole claim

Optional extensions

Same rate, different starting amount

One year or two?

The fee changes the result

More euros, fewer choices?

Practise it — free games & tools

For the teacher

Prepare once

Adapt for your class

Assess the mission

The pupil workbook

Interest

Interest