Please ask your child to watch the video above. Can they discuss with you what we mean by 'half' 'equal' 'share' and 'fair'?
Please ask them to spend some time exploring the idea of sharing using objects from around the house. For example, can they share 6 pencils equally between them and their brother? Or 8 pieces of Lego between themselves and you? Or 6 sweets between 2 plates?
To make things easier at this stage it might be better if you stick to even numbers under 10. Though when you feel they are confident with the idea of halving you could increase the numbers to under 20.