What is depicted on the blackboard?

Analysis of the Blackboard Content:

The blackboard contains handwritten mathematical content and some tabular data at the top. The mathematical content includes:

• Geometric Constructions: There are drawings of triangles, lines with points labeled A, B, and C, and arcs indicating compass use. This suggests problems related to constructing geometric figures.
• Mathematical Notation: Labels like 'A', 'B', 'C', and diagrams imply geometric problem-solving.
• Text: There's handwritten Russian text at the top: 'Классная работа' (Classwork) and 'Построение тр-ков.' (Construction of triangles.). There is also a date '18.05.26'.
• Tabular Data: A grid of numbers is visible at the top of the blackboard, possibly from a wall chart or calendar.
• Other Markings: There are vertical and horizontal lines, some with tick marks, resembling a ruler or grid, and a pink eraser at the bottom.

The overall context points to a geometry lesson focused on constructing triangles.