Mirror image shapes look like the same shape, but when placed in the quilt block they must “mirror” each other.
Learn about quilt patterns that are mirror images.
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TRANSCRIPT: Mirror Image – Encyclopedia
These two shapes are considered mirror images of each other. So that if you were to take this shape up to a mirror and look in the mirror, you would see a shape that looks exactly like this, and vice versa. So why is this so important for quilting? The reason why is because we need to recognize when a mirror image is going to happen in our quilt because it can cause problems if we don’t understand that. So in this basket block, we have a square right here, and a triangle and we have another square and a triangle. Now, if I were to sew these together- I’m going to put right sides together, and take that to the sewing machine. I’m going to put right sides together and take that to the sewing machine. Well on my way to the sewing machine I might saw, oh yeah, here we go, I’ve got 2 squares, 2 triangles and they are going to go in this basket block, so I’m going to sew this seam. But if I were to sew both of those exactly the same, which you might think they need to be sewn the same because they’ve got the same parts, then if I sewed them exactly the same, when I opened them up, what’s going to happen is I’m going to get 2 exactly the same shapes. But these two shapes are not going to fit into my basket. I need to have 2 different shapes that are mirror images of each other so there’s the one and there’s the other one. So when you are doing patchwork blocks, make sure that you pay attention to see if the pieces form mirror images or not.