Happy New Year (1+2+...+9)²=(20+25)²=1³+2³+...+9³

This year is a bit special! It is a square year, demonstrating that (1+2+...+n)²=1³+2³+...+n³ for n=9. Here is a manipulative to show this: a set of squares (or half squares for even numbers) from sides 1 to 9, that you can pile up into cubes! I created this using OpenScad. Actually printing all numbers with a different color looks better, like this in geogebra. IREM de Lyon