Raven opens the Numbers Desk notebook to a page of morning and evening readings. "Five days of our porch thermometer."
"Monday morning was -4," Rocket reads. "Monday evening was 3. So it changed by 1? No, wait."
"What do you notice about the two signs?" Raven asks.
"One is negative and one is positive," Rocket says. "They are on opposite sides of zero."
Nova hovers over the page, her light on the Monday row. "A change is a hop from the morning to the evening," she says.
Rocket hops from -4 to 3 on the paper number line. "Four hops to zero, then three more. Seven degrees!"
"Change is the evening reading minus the morning reading," Raven says. "3 - (-4) = 7."
"Now do all five days," Nova says, "and then our par scores."
These are the crew's own made-up readings, in degrees, for one Field Day planning week. None of them are real weather records.
Change means the evening reading minus the morning reading. A positive change means the day warmed up.
A negative change means it cooled down. The last row is left for you to find.
| Day | Morning | Evening | Change |
|---|---|---|---|
| Mon | -4 | 3 | +7 |
| Tue | -1 | 5 | +6 |
| Wed | -6 | -1 | +5 |
| Thu | 2 | -3 | -5 |
| Fri | -2 | 4 | ? |
Monday: 3 - (-4) = +7. Thursday: -3 - (2) = -5. Thursday cooled down.
The size of a change is the distance between the two readings, the absolute value of the difference.
In Field Day ring toss, par is the expected score. A round above par counts positive, below par counts negative.
Here are the crew's practice rounds. Add the four rounds to find each total above or below par.
| Player | Round 1 | Round 2 | Round 3 | Round 4 | Total |
|---|---|---|---|---|---|
| Rocket | +3 | -2 | +4 | -1 | +4 |
| Raven | -3 | +2 | +2 | +1 | ? |
| Nova's tally | 0 | -4 | +3 | +3 | +2 |
| Number sentence | True or false? |
|---|---|
| 3 - (-4) = 7 | ? |
| -3 - 2 = 5 | ? |
| -3 + 2 + 2 + 1 = 2 | ? |
| -1 - (-6) = 5 | ? |
Excellent data work. Tomorrow you find signed numbers all over everyday life, and review the week.