In math, we've been studying constant rate of change (grown up language only) by thinking about penny jar situations. A penny jar situation might sound like this: I start with 4 pennies in a jar. Each round, I add 5 more pennies to the jar, so after round 1, there are 9 pennies in the jar, and after round 2, there are 14 pennies in the jar. We've been talking about how you can figure out how many pennies are in the jar after any round without having to know how many pennies were in the jar in the previous rounds. There are a bunch of ways to think about this. For example, Charlie noticed,
"If you know the 5th round and want to know what the 8th round is, you have to find out how much is in there, or how much rounds is in between the 5th and 8th rounds. I add the number you're supposed to add (5, in this situation) three times. I add three times because that's what's in between five and eight."
Here's Charlie's explanation of his work for the penny jar situation start with 4, add 5:
