Mrs. Johnson works at a bakery. She is a nice, but elderly lady who really needs to retire from the bakery. One Monday afternoon, Robert went to the bakery after school to order a cake for his mom's wedding. Robert needed the cake on Thursday afternoon by 3:00 pm. Mrs. Johnson said she would have it ready for him. On Tuesday, she started making the cake, but she put too much flour in the cake and it rose up too much in the middle. Mrs. Johnson started over making the cake. This time she put too much sugar in the cake and it cracked right down the middle. Finally, by Thursday morning, Mrs. Johnson had the cake ready to decorate. As she was picking it up to place on the tale where she decorated her cakes, she almost dropped it on the floor. What do you think was the cause of Mrs. Johnson having so much trouble with the cake?