Non-Standard Units
What is a non-standard unit?
A non-standard unit are objects we use to measure that is not an official tool (ruler), like steps, hands, or blocks.
What is a standard unit?
A standard unit is a measurement that is always the same and gives you the same answer.
What does “cm” stand for?
Centimetres.
Name two non-standard units you could use to measure length
Steps, hands, paperclips, blocks (any two).
What standard unit do we use to measure length of objects in our classroom?
Centimetres.
What do the small lines on a ruler show?
Each small line shows 1 centimetre.
Why might two people get different answers when measuring with steps?
Because people’s steps are different sizes.
Why do we use standard units instead of non-standard units?
Because they are the same for everyone and give more accurate measurements.
About how big is 1 centimetre?
About the width of your finger (or a small cube).
Is measuring with paperclips more accurate than measuring with steps? Why?
Yes, because paperclips are the same size, but steps can be different sizes.
Why do we use standard units instead of non-standard units?
Because they are the same for everyone and give more accurate measurements.
Which would you use to measure the length of your pencil: centimetres or steps? Why?
Centimetres, because they are small and accurate, and steps would be too big to measure a small object.
When is it okay to use non-standard units instead of standard units?
When you are estimating, exploring, or don’t have a ruler/measuring tool.
Two students measured the same object. One got 20 cm and one got 30 cm. They both used a ruler. What might have happened?
One of them may not have started at zero, didn’t line up the ruler properly, or measured incorrectly.
A student measured a book and got 14 cm. Then they measured it again and got 16 cm using the same ruler. How is that possible?
They may not have started at zero the first time, didn’t line up the ruler properly, left a gap, or shifted the ruler while measuring, which changed the measurement.