In English grammar there are three degrees of comparison of an adjective. An adjective may simply describe a quality, (the positive); it may compare the quality with that of another of its kind (comparative degree); and it may compare the quality with many or all others (superlative degree).
The positive degree is the most basic form of the adjective, positive because it does not relate to any superior or inferior qualities of other things in speech. The comparative degree denotes a greater amount of a quality relative to something else. The phrase Anna is taller than her father means that Anna's degree of tallness is greater than her father's degree of tallness. The superlative degree denotes the most, the largest, etc., by which it differs from other things.
For worksheets relating to comparisons, you have come to the right place. There are now 289 adjective worksheets available on this topic and they are all free and easy to print out for use in any classroom. This worksheet clearly explains the different ways comparative and superlative words are formed and even includes a couple practice exercises on the last page. You may want to create more blanks on the first five pages so that students can start practicing from the very beginning. Some teachers do not introduce the different types of comparative and superlatives right away. You could introduce just er comparatives and then build on that by teaching students est superlatives or comparatives that are formed by using the word more. However you choose to cover this topic in your class, Busy Teacher can help you. If for some reason you do not find what you are looking for, please create a worksheet of your own and then upload it so that other teachers can learn from you.