The dinosaurs start out very small, you drop them in a glass of water, and several hours later they grow in size. The package says they grow to 400% their original size. I remember these things as a kid and always being extremely disappointed in the result. When you see 400% written on the package, it gives the impression that the dinosaurs will be HUGE after they grow. The dinosaurs do indeed grow, as seen in the picture above. The pink dinosaur is definitely bigger then the yellow and green dinosaurs.
I don't doubt that the pink dinosaur is 400% bigger, but 400% really isn't all that much, especially when the object starts very small. 400% is four times bigger. However, four times bigger doesn't appear much bigger when the object starts off small. My 4 year old was convinced the dinosaur was going to grow out of the glass of water and reach as tall as the cabinets in the kitchen. Sorry little one, but not quite. :-) I think she was a bit disappointed the next morning when she found the dinosaur bigger, but still easily contained within the glass.
The moral of this story? Keep your expectations at a reasonable level and your won't be disappointed. :-)