Finding a fraction of an amount.
Finding the fraction of an amount is quite easy - the teaching examples show you how to find one part of a whole that has been divided into equal parts and then how to calculate say three out of five of those parts, i.e 3/5ths of 40. (First divide 40 into 5 equal parts to find out the value of 1/5 and then multiply by 3 to find 3/5ths.) The teaching examples use a model called a bar model which makes this very easy to visualise, you should practice drawing your own bar models when you are doing the independent practice (if you can draw bar models you'll be good at harder calculations with ratio and scaling later on in year six.)
The teaching examples get a bit harder because they will ask you to do harder calculations, like find 2/3rds of 2.1kgs. Try to look for the connection between the amounts 2.1 kgs divided by 3 is going to be like 21 divided by 3 and you'll find the answer is 0.7kgs. It's tricky but don't panic - this is getting you ready for the fact that the next unit we study will be on decimal fractions and so this practice is getting you used to the idea of working with decimals.