overlap

Everyday

1. To overlap means to cover part of the same space as something else, so one thing lies partly over another. tree →
2. To overlap means to happen partly at the same time. tree →
3. An overlap is the part that is shared or covered twice. tree →

In the lessons

parts that are counted twice: shared members of two groups, overlapping times, or strips that cover each other; in maths: the overlap of two circles in a Venn diagram holds things in both groups; in everyday life: roof tiles and fish scales overlap to keep water out; clubs or lessons overlap in time

Examples

• 12 children like apples, 10 like pears, and 4 like both, so the groups overlap. tree →
• The two boards overlap by 5 centimetres. tree →
• Each tile overlaps the next by 2 cm. tree →
• The two meetings overlap for 15 minutes. tree →
• Write the children who like both in the overlap of the Venn diagram. tree →
• Roof tiles overlap so rain runs off. tree →
• Football and swimming overlap on Tuesday, so I can't do both. tree →
• The circles overlap in the middle. tree →

Note

The shared part must not be counted twice: total = first + second − overlap (12 + 10 − 4 = 18). Trap: adding two groups that overlap gives too many. Trap: two 30 cm strips overlapping by 5 cm make 55 cm, not 60. Past: overlapped (double p).