Ruler for primary school mathematics teaching

The utility model relates to a primary school mathematics teaching ruler which comprises a main ruler body and an auxiliary ruler body, a rectangular containing groove is formed in the main ruler body, a sliding rod and a compression spring are arranged in the containing groove, a sliding block is arranged on the sliding rod, and the two ends of the compression spring are connected with the sliding block and the right side of the containing groove respectively. The right end of the auxiliary ruler penetrates through the right side of the containing groove and extends out of the main ruler, the back of the auxiliary ruler is fixedly connected with the sliding block, a locking groove is formed in the auxiliary ruler and corresponds to the locking assembly, the locking assembly comprises a movable rod and a reset spring, the movable rod penetrates through the main ruler, and a button and a locking block are arranged at the outer end and the inner end of the movable rod respectively. The locking block is located