The gradebook can calculate using 1) only total points or 2) with a combination of points and weights. At the simplest level the points of an individual assignment are used to calculate the grade for the assignment. For example, if an assignment is given 100 points and a student scores 82, the percent of that assignment is 82%. Similarly, if an assignment is given 50 points and a student scores 37, 37/50 = 74%. If no weighting is applied, the final grade will be total points earned across all assignments divided by total points possible across all assignments.
With weighting you can determine the weight of individual assignments within the average at both the assignment and the category levels. For example, within a category such as Tests or Class Work you can weight all the assignments the same or weight some heavier than the others. You still need points to make the percentages for individual assignments (e.g. 37/50 = 74%) but beyond that the points are of no consequence. At the category level you can weight categories such as Tests (perhaps 60%) or Class Work (perhaps 40%) for the final quarter or trimester average.
Best Practices for Most Teachers
Check Use Weighted Categories and have the weights add up to 100. Don't bother with Weighted Assignments unless you have a good reason to do so.
The more points you give an assignment the more it is worth within the category. An assignment with 100 possible points will count 10 times as much as an assignment with 10 points. Come up with a consistent pattern. Use possible points like 5, 10, 20, 50 or 100. Using numbers like 7 make the calculations more difficult to check.