I have recently updated the Summer Maths 2023 post to include the following ideas and resources:
From ATM, see the Summer Solvers series, For Twitter users these are tagged #summersolvers. Each day in August, at 10 am, ATM are posting a problem from their archives for a range of age groups, we have problems to work on for KS2 to KS5 (UK ages 6 – 18).
For August 4th we have Number Spirals, from 30 Years On, a collection of classic mathematical ideas and activities. Note that you can look inside the book and the pdf includes 2 problems, Fractional Triangle and Number Spirals.


August 4th: from Geometric Jolts see this post, Geometric Sparks also Dietmar Kücheman’s blog.
August 3rd Fault Lines from Points of Departure – I recall using Points of Departure when GCSE coursework first appeared!
…and on the subject of GCSE coursework, there are some classics in this old Edexcel document. Who remembers T-Totals and Opposite Corners?!

For many investigations, see this series of pages. Anyone for Diffy?