Here are some number songs. They all focus on taking 1 away, or 1 less.

Here is a link to another Oak National Academy Reception Maths lesson. It focuses on ‘1 less than’. You will need a 10 frame like the one below and 10 small objects. You will also need 1-10 number cards.

https://classroom.thenational.academy/lessons/finding-one-less-than-a-given-number/activities/1

If you cannot access this lesson, try this activity. Turn over a number card – put that many objects onto the ten frame. So, if your child turns over a 5 for example, they put 5 objects onto the ten frame. Ask them to take one object away – how many are left? Verbally reinforce this by saying 1 less than 5 is 4.  Ask your child to write out the calculation (5 – 1 = 4). Repeat this a number of times.