Combine 1/2 cup white glue and 1/2 cup water in a mixing bowl. Stir until combined and the glue becomes runnier.
Add 2 drops of food coloring that matches the color of your play sand and stir until well mixed.
Add 1/4 cup liquid starch and stir until glue begins to thicken. Add another 1/4 cup liquid starch and stir until slime clumps together in a cohesive ball (but it will still be sticky).
Add 2/3 cup play sand and stir until all sand is incorporated. If your slime is still sticky, you can add another 1/3 cup of play sand. It's ok if a little sand drops out of the slime until you have the perfect texture.