One question, repeated: what is the area of this rectangle? Both sides are labelled, and the answer is their product in square centimetres.
Area is where multiplication stops being repeated addition and becomes a shape. A student who can see the rectangle as rows of unit squares has the idea; the drawing is there so that seeing it is possible.
Multiply the length by the width. A rectangle 7 cm by 5 cm has an area of 35 cm².
Because area counts squares, not lengths. A 7 by 5 rectangle holds 35 squares each one centimetre on a side, which is what cm² means.
Yes. Every rectangle is drawn at the ratio its labels state, so a shape marked 12 cm by 4 cm really is three times as wide as it is tall.
Third grade, where area is introduced as covering a shape with unit squares, and again in fourth as a multiplication.