Algebra is only going to become more advanced as the years of school pass and if one has not gained full knowledge of it at its most basic level, it will be impossible to venture on. You have to algebra one step at a time. If you do these steps over and over, your brain will start to adjust and you will like it.
Children usually start to learn about decimals in Year 4. The first thing children need to know is that a decimal is A PART of a whole. A good way to explain this is to show them an empty hundred number square / chart.