Some of my students lacked a strong math background when they came to me. Their fourth grade teacher encouraged the use of a calculator, where I focus on fact recall and how to correctly solve problems mathematically. Two students actually did a happy dance the day we did a division algorithm lesson because they were finally going to learn to do division.
To strengthen math skills, I give math homework twice a week, in addition to the math lessons. My kids love math homework. One of their favorites is from a program called "Drop in the Bucket", a blackline master book from Frog Publications. Students actually cheer when they hear that we are doing a "Drop in the Bucket" as homework. I start with Level D (4th Grade) and work through Level E, which is fifth grade. These are a great way to make sure students are proficient on a particular skill.
When we are studying for a test, I give skill review worksheets I call scrambled eggs. I have included two as freebies.
Addition/Subtraction Scrambled Egg 1
Multiplication/Division Scrambled Egg 2