I loved the Cuisinaire rod set. My school in Australia introduced students in grade 2, possibly grade 1. That was back in 1964-1965, when I was about 6-7. It was helpful to visualize addition, multiplicatio, subtraction, division, factorizing, equivalence of 3x2 and 2x3. My parents even bought a set for my sister and younger brother.Why not just teach algebra, wouldn't that be easier - ie. why not teach the easy way right from the start, instead of teaching them the hard way first? Wouldn't a kid pick up bad habits by thinking in blocks rather than algebraically? (Or is this preparation for powerful diagrammatic methods like Feynman diagrams and graphical models?)Those exercises are visual training for kids to prepare for algebra; they are not 'instead' of algebra.
If you ever teach math to children, you will find physical blocks ('math manipulatives') to be very helpful in conveying concepts. This is just a paper version of making the question out of blocks. Remember the age level of the kids this is aimed at.
Once kids can do the algebra, you don't need stuff like this any more. If a teacher is saying that you 'can't use algebra,' that is a problem with the teacher.
I was surprised when I came to the US that they were essentially unknown, at least where my family was living. I found the US method of teaching math somewhat archaic and unspiring. I skipped half of 3rd grade because of the move, and found 4th grade quite easy, especially when it came to arithmetic as it was called. I had my math workbook confiscated because I preferred to do math problems during music lessons, and the 4th grade teacher was a bit upset that I was way ahead of the class. I also got marks off because I did the math in my head, and I didn't have to cross out numbers when carrying.
On the other hand, I was terrible in English (literature, writing, . . . ) and especially poetry. I found reading fiction stories excruciating because my mind was elsewhere. :uhh: I got into trouble for not reading fiction books, which I didn't because I wanted to read books on geography, rocks and minerals, rockets and spacecraft, . . . . , and occasionally history, or other non-fiction.
And I got D's in hand writing because I just didn't write well. Writing cursive was painfully slow and my hand couldn't keep up with my mind.