To determine how many times Joslani needs to fill his 1/8 teaspoon measuring tool to get 5/8 teaspoon of coloring, we can divide the total amount of coloring needed by the amount his measuring spoon holds.
The calculation is as follows:
\[ \frac{5/8 \text{ teaspoon}}{1/8 \text{ teaspoon}} = 5/8 \div 1/8 \]
To divide fractions, we multiply by the reciprocal of the divisor:
\[ 5/8 \times 8/1 = (5 \times 8) / (8 \times 1) = 40/8 = 5 \]
Joslani will need to fill his 1/8 teaspoon measuring spoon 5 times to get enough coloring to follow the recipe.