### Planning and Activities

**Day 1**Use Spider and Fly on the 100-square to show how to add 10, 1, 11 and 12 to 36. Repeat, starting with 25, 71 and 68.

**Group Activities: T with Y1**

Y1 -- Fill in a table to show which digits change when we add 1, 10 and 11.

Y2 -- Add 12 repeatedly and reason about the patterns made.

**Day 2**Use Spider and Fly on the 100-square to show how to subtract 10, 1 and 11 from 56. Repeat, starting with 48, 72 and 51.

**Further Teaching with Y2**

Ask children to use the digits 3, 5 and 7 to make as many 2-digit numbers as they can and write them in ascending order. Observe how this enables

*finding all possibilities*.

**Group Activities: T with Y2**

*Use the ‘New Neighbours’ in-depth problem-solving investigation below as today’s group activity.*

Or, use these activities:

Y1 -- Fill in a table to show which digits change when we subtract 1, 10 and 11.

Y2 -- Mobile phone keypad investigation. How many 2-digit numbers can be made? Reason about systems for recording/ organising results.

**Day 3**Show two 1-digit cards. Y1: write the smallest possible number, Y2: write both possible numbers and a number in between. Explain the Y1 investigation.

**Further Teaching with Y2**

Join two 100-bead strings together to form a 200-bead string. Show numbers between 100 and 200, recognising similarities with numbers between 0 and 100.

**Group Activities: T with Y2**

Y1 -- Investigate subtracting numbers with reversed digits trying to find as big an answer as possible.

Y2 -- Reason about the position of numbers on a 101–200 square. Play a game to identify missing numbers on a 101–200 square.