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Science Launch G5 / Week 02 / Wednesday
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Week 02 · Nothing Lost

Wednesday

Investigation: Weigh the vanishing sugar
// Weight stays the same when matter changes
⏱ about 15 min

Wednesday: Investigation: Weigh the vanishing sugar

The kitchen table is now a lab. Raven sets out a cup of water, a small paper cup of sugar and the scale.

"Here is the tricky part," she says. "We weigh everything together, both cups, before we mix."

Rocket reaches for the spoon. "Then I pour and stir!"

"And then weigh both cups again," Raven adds. "Even the empty paper cup."

Nova projects a small table in the air. "Why do you think the empty cup must stay on the scale?" she asks.

What you need

  • A kitchen scale (ask a grown-up)
  • A clear cup half full of water
  • A small paper cup with 2 spoonfuls of sugar
  • A spoon for stirring
Safety first
A grown-up sets up the scale and the water.
Stir gently so water does not splash.
Nothing is tasted, even the sugar water.
Wipe up spills right away.

Steps

  1. Put the water cup, the sugar cup and the spoon on the scale together.
  2. Write down the weight.
  3. Pour the sugar into the water.
  4. Stir until you cannot see the sugar.
  5. Put the water cup, the empty paper cup and the spoon back on the scale.
  6. Write down the new weight.
MAKE A PREDICTION
  • Read the question.
  • Tap your answer.
After the sugar dissolves, what will the total weight be?
WhenTotal weight (grams)
Before mixing
After dissolving

Your two numbers should be the same, or very close.

A tiny difference can happen if grains stick to the paper cup or a drop splashes. Scientists call that a measuring error, not lost matter.

Why must the empty paper cup go back on the scale? Type one word: weight or color.
WHY THIS EXERCISEA fair test weighs exactly the same things before and after. Only the change in form is tested.

Reading your results

Compare your before and after numbers.

If they match, your test supports the rule. Weight was conserved.

If they are a little different, think about spills, splashes or grains left behind.

LAB THINKING
  • Read the question.
  • Tap your answer.
Why did you weigh the spoon both times?
A drop splashes out while stirring. What happens to the after weight?
StatementTrue or false?
A tiny difference can come from grains stuck to the paper cup.?
Sugar is destroyed when it dissolves.?
Writing numbers in a table helps you compare.?
WHY THIS EXERCISESmall differences come from errors, not lost matter.

You ran a careful test with fair measurements. Tomorrow we will see what happens when a new gas is made.

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