# Number Lines Friend or Foe?!? 3548279991,236123241.

## Presentation on theme: "Number Lines Friend or Foe?!? 3548279991,236123241."— Presentation transcript:

Number Lines Friend or Foe?!? 3548279991,236123241

How do number lines help us? Rounding Finding a midpoint Ordering numbers Adding numbers Subtracting numbers Skip counting (multiplication) Math

Rounding Round the number to the nearest hundreds place: 765 Old School: Mathematical Thinker: The six is higher than five, so you have to round up. I know that 765 is in between 700 and 800. 65 is greater than the midway point of 750, so it must round up to 800. I also know that on a number line, 765 is much closer to 800 than 700.

Ordering Numbers Put the numbers in order from least to greatest: 54 67 62 Old School Mathematical Thinker: Look at the largest place value, find the smallest number, it goes first. If the numbers are the same, go to the next place value… On a number line, I know that fifty comes right before 55, so I will put it there. Both 62 and 67 are in the 60s, but 62 is closer to 60 while 67 is closer to 70.

Adding and Subtracting Solve 345 + 267 Old School Mathematical Thinker 345 + 267 612 5 + 7 is 12, so I put down the 2 and carry the 1. I know that if I add 200 to 345, I will jump to 545. Then if I add another 5, I am at 550…. 345550545600610 +200+5+50+10+2 612

What happens when students don’t think about numbers

Your turn! No groaning! 873 + 289 = 12, 352 + 9,236 = 4,123 – 956 =