By grade 4 they start programming in Logo. Starting with sequences of commands, then progressing to loops.
By grade 5 they are writing procedures containing loops calling procedures containing loops.
At this point a quick comparison with the United States is in order. A couple of visits to San Francisco’s magnet school for science and technology (Galileo Academy) revealed grade 11 and 12 students struggling with HTML’s image tag. Loops and conditionals were poorly understood. Computer Science homework was banned by the school board.
It is an understatement to say that I was impressed with the Vietnamese primary school CS curriculum. I asked what I could do to help. Unexpectedly, the answer was “software”. Educational software doesn’t even exist in Vietnamese, and even if it did exist, there was no budget to purchase any. So the rest of my vacation was spent writing software. The result was the Blockly Maze, a self-teaching set of tutorials that introduces loops and conditionals. Everything had to be burned to CD because the school couldn’t afford reliable Internet.