Many of my 7th graders struggle with expressing their mathematical thinking in writing. In particular, I’ve noticed that they struggle with generalizing ideas and with explaining why their strategy works and makes sense.
Writing about adding and subtracting signed numbers seemed like fertile practicing ground, so I created a digital journal with reflection questions on Desmos.
Some of my students really did go deep and explain their sense-making. Others continue to simply report what they did. Their writing also unearthed several misconceptions and showed me that many students are still using the word “bigger” to describe negative numbers that are farther from zero than positive numbers.
How would you explain what negative numbers are to a kindergartener?
What do you wonder about negative numbers? Think of two juicy questions.
(I love asking kids to ask their own mathematical questions….and I don’t do enough!)
Choose one of the problems from the table and explain how you thought about it. I want to know exactly how you came up with your answer and why your method makes sense.
In all of these problems, you were asked to add a negative number and a positive number together. Sometimes the answer was positive and sometimes it was negative. Why does this happen?
Why do all of these problems have negative solutions? Explain in detail.
Suggestions – for me, my students, or the activity are always welcome!