Answer :
His number line is incorrect, or he plotted the point incorrectly. We know that the numbers on a number line get bigger as we get farther and farther away from zero on both sides. So -4 being closer to zero than -2 is impossible on a perfect number line. Thus, he either needs to check his counting, or check if he plotted the right number.
5
4
3
2
1
0
-1
-2
-3
-4
-5
5
4
3
2
1
0
-1
-2
-3
-4
-5