Combine rhubarb, juice, and sugar in a medium saucepan and bring to a simmer over medium heat. Simmer, stirring occasionally, until rhubarb is very soft, about 5 minutes.

Pour mixture into a blender and cover with a dish towel (don't put the lid on, the mixture is too hot and the lid might blow off when you turn on the machine). Hold the dish towel over the blender and blend until smooth.

Strain rhubarb mixture through a fine mesh strainer set over a bowl. Press down on the solids to extract all the juice. You can also just make the paletas with the unstrained mixture, they won't be a clear pink color but you probably will get an extra paleta or two. If you do strain it you can save the rhubarb pulp (which at this point is really more like a sauce) and spread it on toast, mix into oatmeal, or spoon over ice cream.

Place a few strawberry slices in the bottom of each paleta mold, evenly distribute the rhubarb mixture between the molds, insert the popsicle sticks and freeze at least 4 hours or until solid.