counting something usually requires seeing that something & we need a tool to count the legs of an ant ->  to count the legs of an ant requires seeing the ant  an insect usually has a small size & an ant is a kind of insect ->  an ant is small in size  an ant is small in size & seeing small things is difficult ->  seeing an ant is difficult because an ant is small in size  seeing an ant is difficult because an ant is small in size & magnifying glass is used to see small things by making objects appear bigger ->  magnifying glass can be used to see an ant by making it appear bigger  to count the legs of an ant requires seeing the ant & magnifying glass can be used to see an ant by making it appear bigger ->  magnifying glass can be used to count the legs of an ant by making the ant appear bigger  magnifying glass can be used to count the legs of an ant by making the ant appear bigger & a hand lens is a kind of magnifying glass -> a hand lens can be used to count the legs of an ant