This document provides teaching notes for a lesson that introduces students to investigating the minimum number of handshakes needed for different numbers of people to greet each other. The lesson begins with an introductory animation to engage students. Students are then guided through a systematic investigation of different numbers of people using interactive software that counts handshakes. In the plenary, students analyze the data collected and are encouraged to identify patterns and explain their findings to the class.

1. Teachers’ notes
Introduction
• Show children starter animation
• Ask children for suggestions about the
minimum number of handshakes needed
for 3 people to greet each other.
• Show children the animation for 3 people.
Main session
• Show children the main question to be
investigated.
• Discuss how to go about investigation.
• Bring up each thought bubble one at a
time.
• Write in the children’s suggestions for
each bubble.
• Show children how to change the number
of people on the screen.
• Show them how to drag the people. (Each
person has to be dragged to the grey dot
in front of the other person to get them to
shake hands)
• Point out that the counter is keeping a tally
of the number of handshakes.
• Ask the children to come out to the board
to work out the minimum number of
handshakes for different numbers of
people.
• Encourage them to take a systematic
approach.
Plenary
• Ask children to give suggestions for
number of handshakes for 20 people
giving reasons for their suggestions with
data they have collected.
• Fill in table, ask children to point out
patterns in the results.
• Encourage children to come out to the
board and explain their findings using
diagrams and jottings.