Why is the measuring jug straight-sided?

Because a jug that tapers holds more per centimetre at the top than at the bottom, so a liquid level drawn in proportion to the volume would be wrong at every value except empty and full. Textbooks draw straight-sided jugs for the same reason. The spout and the handle are the only jug-shaped parts.

Can the level sit between two marks?

No. It snaps to the nearest small mark, because a scale you can set between the marks is a scale with no answer. 23.4 degrees on a thermometer marked in twos is not a question anybody asked.

How do I use it for negative numbers?

Switch to the thermometer and press below the gold line. It goes down to minus 20, and the line shows where zero is, so a class can see that minus 5 is below zero rather than just reading a number with a sign on it.

How do I set up a question?

Set the level, choose what the small marks are worth, then tap Hide. The caption tells the class what one mark is worth and the number is gone, so counting on from the last numbered mark is the work left to do.

Reading Scales

Measure · Year 2–Year 6

A thermometer and a measuring jug. Hide the reading and read the scale.

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About the reading scales

Two instruments that are the same instrument twice: a column, a scale beside it, and a level to read off. Press the column where you want the level and it goes there, on the nearest mark.

The hard part of reading a scale is never the number at the top. It is working out what one small mark is worth, so that is the control: small marks of 1, 2 or 5 on the thermometer, 10, 25 or 50 on the jug. The same level reads differently once the marks change, which is the point.

Turn the reading off and the class works it out. The caption then says what a small mark is worth, because that is the step to give them, not the one to test.

The thermometer goes down to minus 20, with zero drawn right across the column in gold. Negative numbers in context are on the curriculum from Year 4 and nothing else here can show one: a level below that gold line is what below zero looks like.

How to use it on your whiteboard

1Press the column, or the numbers beside it, at the level you want.
2The plus and minus buttons move the level one small mark at a time.
3Each small mark changes what the unnumbered marks are worth.
4Reading hides the number so the class can work it out.
5Tap Fullscreen so the instrument fills the board.

Questions

Why is the measuring jug straight-sided?: Because a jug that tapers holds more per centimetre at the top than at the bottom, so a liquid level drawn in proportion to the volume would be wrong at every value except empty and full. Textbooks draw straight-sided jugs for the same reason. The spout and the handle are the only jug-shaped parts.
Can the level sit between two marks?: No. It snaps to the nearest small mark, because a scale you can set between the marks is a scale with no answer. 23.4 degrees on a thermometer marked in twos is not a question anybody asked.
How do I use it for negative numbers?: Switch to the thermometer and press below the gold line. It goes down to minus 20, and the line shows where zero is, so a class can see that minus 5 is below zero rather than just reading a number with a sign on it.
How do I set up a question?: Set the level, choose what the small marks are worth, then tap Hide. The caption tells the class what one mark is worth and the number is gone, so counting on from the last numbered mark is the work left to do.