← Maths with Martin

Level 4 free

Percent kid

Year 7: percentages, ratio, proportion and triangles. 30 lessons.

1. Rational numbers Whole numbers, fractions and decimals belong to one family. You will learn to line them up on a number line. ⏱ 15 minutes Practice
2. Multiplying fractions Numerator times numerator, denominator times denominator. And the cross-cancel trick that saves you work. ⏱ 15 minutes Practice
3. Dividing fractions Dividing by a fraction = multiplying by the reciprocal. One flip and division becomes the multiplication you already know. ⏱ 15 minutes Practice
4. Compound fractions A fraction inside a fraction is not a monster. The main fraction bar means divide — and you already know that. ⏱ 14 minutes Practice
5. A percent: a hundredth of the whole One percent is one hundredth of the whole. Anyone who gets this has percentages in their pocket. ⏱ 15 minutes Practice
6. How much is 15% of 200 Two reliable paths to a percent of a number: via one percent and via a decimal. ⏱ 15 minutes Practice
7. I look for the whole (the base) You know the part and the percent, but not the whole. The way back goes via one percent. ⏱ 15 minutes Practice
8. How many percent is that Part over whole, times a hundred. The third and last type of percent question. ⏱ 15 minutes Practice
9. Discounts and price rises The new price in one multiplication: 20% off means times 0.8. And why a discount and a rise by the same percent are not opposites. ⏱ 16 minutes Practice
10. Interest in one sentence Interest is a percent of a deposit for a year. One sentence, one calculation — and you understand saving and loans. ⏱ 14 minutes Practice
11. Per mille Per mille is a thousandth of the whole — the younger sibling of a percent. Road gradients, solutions and fine measurements. ⏱ 14 minutes Practice
12. Ratio: 2 : 3 A ratio is a recipe for mixing and sharing. You will learn to read it, simplify it and expand it. ⏱ 15 minutes Practice
13. Share in a ratio Share money or anything else in a ratio: add the parts, find one part, share. ⏱ 15 minutes Practice
14. Map scale A scale 1 : 50 000 is a ratio of the map and reality. Read it, convert centimetres to kilometres and plan a trip. ⏱ 16 minutes Practice
15. Direct proportion Twice as many rolls, twice as many korunas. You will recognise direct proportion and its table. ⏱ 15 minutes Practice
16. Inverse proportion The more painters, the fewer hours. The second kind of proportion, where you multiply across. ⏱ 15 minutes Practice
17. The rule of three A universal writing with arrows that solves direct and inverse proportion without thinking where you divide and where you multiply. ⏱ 16 minutes Practice
18. Kinds of triangles Equilateral, isosceles, scalene. Acute, right-angled, obtuse. And the sum of the angles always 180°. ⏱ 15 minutes Practice
19. Constructing a triangle Draw a triangle from three sides by the SSS rule: sketch, plan, construction, check. ⏱ 17 minutes Practice
20. Heights and medians A height is a perpendicular from a vertex to the opposite side, a median joins a vertex to the midpoint of a side. We draw both. ⏱ 16 minutes Practice
21. The circumcircle and the incircle The circumcircle goes through the vertices, the incircle touches the sides. Perpendicular bisectors and angle bisectors find their centres. ⏱ 17 minutes Practice
22. Quadrilaterals Parallelogram, trapezium, rhombus and company. The family tree of quadrilaterals and their properties. ⏱ 15 minutes Practice
23. The area of a triangle The area of a triangle = a side times the height to it, divided by two. Why it holds and how not to slip. ⏱ 15 minutes Practice
24. The area of a parallelogram and a trapezium A parallelogram = a rearranged rectangle, a trapezium = the average of the bases times the height. Two formulas, one idea. ⏱ 16 minutes Practice
25. Prisms: surface area and volume A prism is a base pulled up into a height. Volume = base times height, surface area = two bases plus the lateral surface. ⏱ 17 minutes Practice
26. Point symmetry A turn of 180° around a centre: every point jumps to the other side, equally far. Construction and spotting. ⏱ 15 minutes Practice
27. Word problems with percentages A strategy for percent word problems: find the whole, the part and the percent, decide what is missing, and calculate. ⏱ 16 minutes Practice
28. Word problems with the rule of three A mix of questions on direct and inverse proportion: recipes, building, speeds. The arrows decide. ⏱ 16 minutes Practice
29. Project: a discount flyer under a lens Take a real flyer and check it: recalculate the discounts, compare prices per unit and find the tricks. ⏱ 17 minutes Practice
30. Percent kid finale A big revision of the whole level: fractions, percentages, ratios, proportions and geometry in one closing circuit. ⏱ 17 minutes Practice

Coding is still on the home page — this course does not replace it.