One of the great things about my role(s) this year is that I have had the opportunity to meet some fantastic Maths teachers and educationalists and last week I hosted Mike Ollerton for two separate events. Mike has made many significant contributions to Mathematics education over the years and he has kindly permitted me to write about the ideas he shared with us last week.

This is a simple activity that feels quite fun and personal but could lead to some rich discussions. Mike’s description of it is here:

After going round the class, asking several children for their BDVs, there are many questions which might present themselves. Can you ask children to work out someone else’s birthday given their BDV? Mike suggests lots more questions:

- Which BDVs only have one birth date?
- What are the minimum and the maximum BDVs in a class?
- Which BDVs have the most dates?
- What is the smallest BDV which cannot be made?
- What is the largest unique BDV?
- Which dates are square BDVs?
- Which dates are triangular BDVs?
- In a group of people who has the average BDV?

What other problems can you devise based upon BDVs?