② Some wide angles in mathematics can be regarded as Olympic math problems. Such as: chickens and rabbits in the same cage, looking for defective products ...

③ One-dimensional linear equations must be mastered;

④ Some differences between positive and negative numbers; (Note: 0 is neither positive nor negative)

⑤ Application of graphics. For example, two straight lines on a plane are either intersecting or parallel (how to draw parallel lines, how to draw a square rectangle parallelogram, etc. ) ...

⑥ Area of triangle = ah ÷2 (base × height ÷2)

Area of parallelogram = ah (base × height)

Trapezoidal area = (a+b) × h ÷2 ((upper bottom+lower bottom) × height ÷2).

The area of a square = a? (side length × side length)

Area of rectangle = AB (length× width)

⑦ decimal system of units

Decimal unit of length:

1 cm =10mm

1dm (decimeter) = 10cm (cm) = 100mm (mm)

1m (m) = 10dm (decimeter) = 100cm (cm) = 1000mm (mm)

1 km =1000m

Decimal system of area units:

100mm？ (mm2) = 1cm？ (square centimeter)

100cm？ (square centimeter) = 1dm? (square decimeter)

100dm？ (square decimeter) = 1m? (square meters)

10000m？ (m2) = 1hm (hectare)

100hm (hectare) = 1km? (square kilometers)

Volume base unit:

1cm？ (cubic centimeter) = 1000mm? (cubic millimeter)

1dm？ (cubic decimeter) = 1000cm? (cubic centimeter)

1m？ (m3) = 1000dm？ (cubic decimeter)

1 l = 1000 ml

⑧ Representation of number pairs

Pet-name ruby triangle properties: Trilateral properties (the sum of two sides of the triangle is greater than the third side, but the difference between the two sides of the triangle is smaller than the third side), and the sum of the internal angles of the triangle is 180, so the triangle is stable. ...

Ah, about so much. Others may not be summarized in place. More than half an hour. . Hoo hoo. I hope the landlord will adopt ~ ~ ~ This is something that Xiao Sheng must master in Grade One. . .