This
activity is good for helping pupils to work and talk together.
It will encourage them to 'play' with $25$ objects and
give reasons for choices.
Possible approach
After saying the riddle orally, you may wish to
display it on a screen or have it written on a board so everyone
can see. Allow pupils to choose whatever resources they
think they'll need to try to find a solution and
encourage discussion.
Key questions
Tell me about your lines.
Possible extension
Children could find a variety of answers and create new
problems that are similar for others to do.
Possible support
Any help that will enable the pupil to talk openly would be
good.