4.MD.A.2

Use the four operations to solve word problems involving distances, intervals of time, liquid volumes, masses of objects, and money, including problems involving simple fractions or decimals, and problems that require expressing measurements given in a larger unit in terms of a smaller unit. Represent measurement quantities using diagrams such as number line diagrams that feature a measurement scale.

Use the four operations to solve word problems involving measures of distance, time, volume, mass, and money. Problems should include fractions or decimals, and problems that require expressing a larger unit of measure in terms of a smaller one.

Concude by giving your students this challenge:

Neighbours by NRICH: Here's the solution: Suppose house 3 is somewhere along the top row, and house 10 is somewhere along the bottom. Setting houses 3 and 10 to be in the rightmost-column, and reading the house numbers clockwise, gives us [3][4, 5, 6, 7, 8, 9][10]. Notice the right column of houses has 6 houses in it, so the total number of houses in the square is \(6 \cdot 4 = 24.\) If we move houses 3 and 10 to the left one column, we get [3, 4][5, 6, 7, 8][9, 10]. In this case, the number of houses in the right column is 4, so the total number of houses in the square is \(4 \cdot 4 = 16.\) Suppose we try to move houses 3 and 10 another column to the left. This would give us [3, 4, 5][6, 7][8, 9, 10]. But this is no longer a square, it's a rectangle. So the smallest number of houses in the square is \(16,\) and the largest number of houses is \(24.\) Ask students why there's no solution with an odd number of houses along each edge? Here's the answer: First, notice that there are exactly 6 numbers between 3 and 10. If we look at our second solution, from before, we see 3 is opposite 10, and 4 is opposite 9. Because each number along the top strip is opposite some number along the bottom strip, the total number of houses along the top and bottom strip, to the right of 3 and 10, will be some even number. We want to add the number of houses per strip to this even number to get 6. But 6 is an even number, and even plus odd is odd. Thus, the number of houses per strip cannot be odd.