Have you noticed that in the picture for 4+5+6+7+8+9+10 the rectangle has an even length and an odd height

How about a diagram representing 8+9+10+11+12+13+14+15+16+17?

What can you say about the length and height of the rectangle in this case?

Is there a general rule?

Always?

Creating and manipulating expressions and formulae. Polynomial functions and their roots. Circle properties and circle theorems. Expanding and factorising quadratics. Odd and even numbers. Generalising. Mathematical reasoning & proof. Regular polygons and circles. Triangle numbers. Inequalities. Simultaneous equations.