standard_description: Use a pair of perpendicular number lines, called axes, to define a coordinate system, with the intersection of the lines (the origin) arranged to coincide with the 0 on each line and a given point in the plane located by using an ordered pair of numbers, called its coordinates. Understand that the first number indicates how far to travel from the origin in the direction of one axis, and the second number indicates how far to travel in the direction of the second axis, with the convention that the names of the two axes and the coordinates correspond (e.g., x-axis and x-coordinate, y-axis and y-coordinate).
problem_activity: Problem 1
a.   Solve.
6 × 3 = _____
60 × 3 = _____
60 × 30 = _____
b.   What do you notice about Part (a)? What do you wonder?
Problem 2
a.   Kristen and Rajiv are finding the product 80 × 50. Kristen says to find 8 × 50, then multiply by 10. Rajiv says to find 80 × 5, then multiply by 10.
Will both Kristen and Rajiv’s methods give the correct product? Why?
Write expressions to represent Kristen and Rajiv’s methods.
b.   Find the product 80 × 50.
Problem 3
Estimate the following products.
a.   41 × 32
b.   57 × 45
c.   24 × 77


aligns: no