Look at the balance scales on the board. Six cubes sit on one pan and six cubes sit on the other, and the beam hangs perfectly level.
What does it mean when the two pans hang level like that?
Show the level balance (the IWB beam, or real scales if you have them) as pupils settle. Take two or three hands-up answers, not open call-outs.
Listen for the key idea: both sides hold the same amount. If a pupil says "they weigh the same", revoice it toward value: so both sides are worth six.
The value of a pan is how much it is worth altogether. Watch two balances on the board. Each one holds different things on the two pans, but every beam hangs level. Look for what has to be true about the two sides for the beam to stay level.
Now watch a beam that does not hang level. Get ready to say what would fix it.
Point at each pan and add the value aloud, then to the level beam: same on both sides, so it hangs level.
Do not read the equals sign as "the answer" — say both sides are worth the same every time.
Today we level the beam ourselves. There is already a value on one pan. We build a matching value on the empty pan until the beam hangs level.
The letter on the empty pan is just a stand-in for the value we do not know yet and are going to build. The loaded pan we start with shows 4 + 3, so we build a matching value on the other pan until the beam hangs level.
Talk this one through together — pupils take turns at the board and the class agrees or corrects out loud.
The interactive is loaded with 4 + 3. Once the class has levelled it, reload the loaded pan with the next value and run it again — work through 6, then 5 + 5, then 4 + 4.
Pacing between rounds: before each build, ask the class to say what the loaded pan is worth. Watch for pupils who split the matching value into two blocks (2 + 5 for 7) — revoice it: different blocks, same total, still level. A turn-and-name keeps watching pupils with you across the four rounds.
In your maths copy, write three true balances using the equals sign, for example 5 + 2 = 7.
Then write one statement that is not balanced, and show why it does not balance.
Walk the room glancing at whether both sides really match — this is whole-class copybook practice, not marking. Nudge pupils who write only "answer" sums (7 = 7) toward a split like 5 + 2 = 7.
Now we do it the other way round. Instead of building blocks, we set the missing number ourselves and press Check to test our prediction. Each time, work out the full pan first, then set the missing number to match it.
These pans hold bigger values than before, so work carefully. We work these in order: level 8 + 5, then 9, then 7 + 6, then 6 + 6.
This is the practice round — pupils take turns at the board, check each answer, and the class confirms before moving on. The values are bigger than the Try It Together round, so give pupils a moment to add before they set the missing number. Keep the board work brisk rather than over-explaining.
Before the reveal on each one, ask the class to predict where the missing number must land. Use the Check as part of the narration: yes — that levels it.
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