When teaching children how to solve word problems, many teachers model how to solve the problem on the board with a diagram and think-aloud (going through each step/thought process). A great digital tool to use is a site called Thinking Blocks. It allows teachers to model how to draw/label a diagram for addition, subtraction, multiplication, and division. As the website states, word problems are easier to solve when you build a model first.
In our math centers, we have been focusing on adding and subtracting two and three digit numbers. To help my kids remember the steps, they reference these posters at our centers.
Since students need different levels of support, counters, number lines, and pictures are used to help students understand the concept. In particular, I found that using a 0-20 number line was very helpful for my students who were having a hard time. The other number lines featured can be useful if you teach students to estimate their answer.