Final answer:
To increase the length of a blood smear, use more blood on the slide and make longer, smoother movements when creating the smear.
Step-by-step explanation:
To increase the length of the blood smear, you can try two things. First, ensure that you are using enough blood on the slide. If the blood droplet is too small, it will result in a short smear. Second, adjust your technique to make longer, smoother movements with the spreader slide when creating the smear. This will help to evenly distribute the blood along the length of the slide and create a longer smear.