Concept of average - 4th grade math
A basic explanation of what AVERAGE means in math — we take a bunch of numbers and consider their sum, and sort of "even them out" so that the sum remains the same. To find the average, you add up all your numbers and divide by however many there are.
Then I use the concept of average to solve a few word problems, including one where we need to use a bar graph, and another where we need to give an estimate based on the calculated average.
See also
Remainder in division-related word problems — video lesson
Math Mammoth Division 2 — a workbook with worksheets and lessons for long division, remainder, factors, and primes
Math Mammoth Grade 4 curriculum