Spread a few spoonfuls of sauce on the bottom of crockpot to avoid noodles sticking.
Break uncooked lasagna noodles into pieces; place ⅓ of the broken lasagna noodles in a layer on bottom of the pot.
Pour about ⅓ of the sauce evenly over the noodles.
Next, place ½ of the ricotta and ⅓ of the mozzarella over the sauce.
Place ½ of the browned ground beef on top of the cheese, followed by half of the pepperoni and mushrooms.
Place a few spoonfuls of sauce lightly over the meat.
Repeat the layers starting with the broken noodles, sauce, cheeses, meat, and a little more sauce.
Finally, layer the last ⅓ of the broken noodle pieces over the top.
Cover noodles completely with remaining sauce.
Sprinkle remaining mozzarella cheese over the top.
Pour water around the edges; cover and cook on low for 3 hours.
Note about cooking time: Cooking times vary greatly depending on the size of your crockpot as well as its cooking temperature. You may find that it takes longer for the meal to cook in your crockpot, so be sure to allow for variance.