Read a stock chart in class: three claims and an answer key

Prepare a 35-minute session

Allow five minutes to read the axes and assumptions, ten for the three claims, ten to compare calculations and ten to mark a new interval and summarise. Students work in pairs with a calculator. Display the chart on screen if useful; the table also contains every value needed for a printed worksheet.

The company and prices are fictional. Each point represents the first day of the named month in an invented year. Lines connect those observations; they do not show every daily price between them. The vertical scale starts at zero. This model has no fees, dividends, deposits or currency effects. All monetary amounts are in SEK.

Student materials: one chart, five observations

Test claim A: The price rose throughout January–May. Test B: From February to May, the price rose by more than 30%. Test C: After April, the price has only fallen, so the next observation must also be lower. Write down the points you use and whether the statement concerns an endpoint comparison, every subperiod or the future.

Also calculate January to May and April to May. Express each result first in money per share and then as a percentage. Mark the starting point on paper before calculating. For A, distinguish a higher ending price from a price that rose in every observed subperiod.

If the table does not fit, scroll it sideways.

Answer key: the selected period defines the result

January to May gives +SEK 10 and 10 / 100 × 100 = +10%. Yet January to February gives −20%, and April to May also falls. A is therefore too imprecise: the ending price exceeds the starting price, but the price did not rise in every observed subperiod. A precise statement identifies the two observations being compared.

February to May gives +SEK 30 using SEK 80 as the base: 30 / 80 × 100 = +37.5%. The fictional material supports B. April to May gives −10 / 120 × 100, approximately −8.33%. That interval supports a fall there, but it does not establish the future price asserted by C.

If the table does not fit, scroll it sideways.

Teacher notes: ask students to defend the interval

Have pairs exchange worksheets and find a conclusion with no named starting point. The other pair improves the sentence without changing its figures. If a student divides every difference by 100, ask whether January really starts every question. If the connecting line is treated as all daily prices, return to what the table actually contains.

Discuss the difference between a price change and an owner’s result. There is no dividend or fee here. A real holding can have additional items affecting its return, and the purchase time must also be specified. A chart alone does not determine that entire result.

Finish with one sentence the table can support and one question it cannot answer. Assess clear intervals and evidence, rather than a student’s view of the next price. A digital follow-up is to read how Investiq presents company information and check which period a figure refers to.