There's also the table method (hahaha its strange but it works and doesn't require remembering much).
You could do it by writing out a table with they x and y, then writing 1 4242424242.......1 and then multiplying w and y for each and then finding the sum of all the wy and multiplying it by h/3. h being the amount between an x value ( eg 3-2 = 1)
Table:
x |-1 | 0 | 1 | 2 | 3 |
y |0.5 | 1 | 2 | 4 | 8 |
w | 1 | 4 | 2 | 4 | 1 |
wy| 0.5| 4 | 4 | 16| 8 |
Sum - 32.5 x 1/3
= 10.8333