Children in Chinese Year 1 classrooms build mental maths on a few clear ideas. Each game here practises one of them. Tap the green speaker to hear any question read aloud.

• 分与合 Split and join. Every number up to 10 is two smaller numbers (7 is 3 and 4). Children drill these until they are automatic, often drawn as a "number bond" tree.
• 凑十 Ten friends. The pairs that make 10: 1 and 9, 2 and 8, and so on. These are the backbone of everything that follows.
• 凑十法 Make ten. To work out 8 + 5, take 2 from the 5 to fill the 8 up to 10, then add what is left: 10 + 3 = 13. This replaces counting on one by one.
• 算盘 Abacus. A top bead is worth 5 and each bottom bead is worth 1, so 7 is seen as 5 and 2. The traditional suanpan has 2 top and 5 bottom beads per rod; this game uses the simpler 1 and 4 school abacus.
• 想加算减 Think adding to take away. For 8 − 3, children ask "3 and what make 8?" and use the number bonds they already know. Take Away uses this on Hard.
• 破十法 Break ten. For 13 − 5 there are only 3 ones, so take the 5 from the ten instead: 10 − 5 = 5, then add the 3 ones back to get 8. This is the partner of Make Ten.
• 几个几 Groups of. Multiplying starts as "how many groups of how many": 3 groups of 5 is "three fives". Children then chant the 九九 times-table rhyme, where 3 × 5 is 三五十五, "three five fifteen".
• 平均分 Share evenly. Division starts as sharing out one at a time until everyone has the same. On Hard, children use the times rhyme in reverse to find the answer.

How tricky? Easy uses small numbers and lots of dots to count. Medium covers numbers to 10 and adding to 18. Hard takes away the counting help, uses teen numbers, and makes children work out each step themselves. The level applies to every game and can be changed at any time.

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