[header] How to make blueberry banana muffin mix in a jar [title] Clean a 1 quart wide mouth canning jar. [title] Layer the ingredients. [step] Be sure to follow the list from top to bottom; start off the layers with the baking soda first and flour last. 
[substeps] Ensure that all ingredients fit in the jar; always be sure to firmly press each one down before adding the next one. You can use the back of a spoon to achieve this.