In the third grade, there are <<19=19>>19 students
In the fourth grade, there are 2 × 19 = <<2*19=38>>38 students
Counting the boys and girls in the second grade, there are 10 + 19 = <<10+19=29>>29.
There are 19 + 38 + 29 = <<19+38+29=86>>86 students in total.
#### 86