Secondary
Give the variable a meaning
Suppose notebooks cost 25 baht each. Let n be the number of notebooks and C the total cost, giving C = 25n. Discuss how changing n affects C rather than only substituting numbers.
Use a table and graph
Tabulate 1, 2, 3 and 4 notebooks and their costs, then plot the points. Ask whether the change is consistent and what the slope says about the price per notebook.
The points represent whole notebook counts of 1, 2, 3 and 4. Each additional notebook adds 25 baht to the total.
View larger image ↗Check the context
Here, notebook counts must be non-negative whole numbers even though the equation allows other values. Checking whether an answer makes sense in context is part of using algebra.
Keep exploring together
Choose activities that match the learner’s knowledge and readiness, and discuss what you notice. Explore the curriculum or parent guide below.