dan meyer's 3 acts
Each person should think of a minimum time and a maximum time, then an estimate of what you think the answer is.
How accurate will each of your measurements be?
Can you measurements be exact? Can your answer be exact?
Why is it important to be able to estimate quantities?
- In groups of four, make a full sized, scale model of the water tank. As you are constructing it, take notes on the following:
How accurate will each of your measurements be?
Can you measurements be exact? Can your answer be exact?
Why is it important to be able to estimate quantities?
- Now, round off the given dimensions to a sensible value. Calculate the volume of the water tank.
- Then, using the given dimensions, calculate again.
- Compare the three 'answers'. Discuss.
estimation, what are you good for?
We estimate consciously or unconsciously ALL of the time. We estimate to get a "ballpark figure" for any problems we are trying to solve at the time. Estimation is a skill that gets better with practice and is really useful in our day to day life. So, as we move through our estimation activities, think about what your brain is actually doing when it gives you an "answer" to the problems.
Rounding using TIDY numbers
Tidy numbers are any number that ends with in a zero. For example, 50, 200, 9000, etc. The most useful tidy numbers to use when rounding are 10s, 100s, 1000s, etc. We can round off the numbers BEFORE we do any calculations. This will again give us a ballpark figure; an estimation. We have to be wary when relying solely on a calculator …. sometimes WE press the wrong buttons. By rounding first and estimating the result, we can get a good idea if the calculator answer is correct!
Rounding using TIDY numbers
Tidy numbers are any number that ends with in a zero. For example, 50, 200, 9000, etc. The most useful tidy numbers to use when rounding are 10s, 100s, 1000s, etc. We can round off the numbers BEFORE we do any calculations. This will again give us a ballpark figure; an estimation. We have to be wary when relying solely on a calculator …. sometimes WE press the wrong buttons. By rounding first and estimating the result, we can get a good idea if the calculator answer is correct!
Rounding
It is often necessary to round off a calculated answer. Rounding depends upon what level of accuracy you require. There are different ways of rounding a number, but all of them use the same technique which uses the middle value e.g. ending in a 5, 50, 500, 0.5, 0.05 etc. There are three ways of rounding:
---to the nearest whole number or integer
---using decimals places
---using significant figures (have a look at the Significant Figures page for more information on this type of rounding)
It is often necessary to round off a calculated answer. Rounding depends upon what level of accuracy you require. There are different ways of rounding a number, but all of them use the same technique which uses the middle value e.g. ending in a 5, 50, 500, 0.5, 0.05 etc. There are three ways of rounding:
---to the nearest whole number or integer
---using decimals places
---using significant figures (have a look at the Significant Figures page for more information on this type of rounding)