Useful outcome: Replace two five-groups with one ten-group without changing or duplicating the collection.
Prepare: Forty actual marks/eight fives, blank ten-group boundaries; fifty and sixty ordinary sets. A frame stands for a full group only after member audit.
Notice · 3 minutes
Place two full fives beside each other. Ask how many objects together and how they might become one counting unit. Do not add a replacement ten model to the old objects as a further ten.
Model · 5 minutes
Forty marks as eight fives count 5…40. Pair the fives to make four tens using the same objects; count 10,20,30,40. The step size and number of groups change together. The total stays 40.
Guided attempt · 8 minutes
Use sixty as twelve fives or six tens. Let the child choose which grouping to use and check the alternative. Discuss different numbers of counting steps, without valuing speed or declaring one method universally best.
Own choice · 6 minutes
Choose one route; the child selects/directs the mathematical action. A different route is available later.
Route A · Catalogue panels
Child task: Pair eight five-panels into four tens and give the object total both ways.
Teacher move: Use the same objects, with a new boundary or directed movement; remove obsolete count pointers.
Observe: 40 in both accounts; replacement rather than duplicate inclusion.
Next move: If 80 appears, match the one collection to each representation and replace boundaries on a new ten-mark case.
Route B · Certificate plan
Child task: Count sixty symbols as chosen fives/tens, then show why another grouping agrees.
Teacher move: Ask why group count changes when group size changes.
Observe: 12 fives or 6 tens give 60; a group count alone is not the total.
Next move: If 6 is reported, audit one ten and count the first two tens before a new collection.
Route C · Which steps?
Child task: Fifty marks can be ten fives or five tens. Compare the two complete count accounts.
Teacher move: Ask whether fewer counting steps means fewer actual marks; match objects before changing boundaries.
Observe: 5…50 and 10…50 end at 50; different steps cover the same set.
Next move: If the smaller group count is treated as smaller quantity, pair two fives into one ten and recheck another set.
Exit and same-day next teaching · 3 minutes
Show four full fives and replace them with two tens. Ask how many objects before and after.
Teaching reference: 20 both times; four five-groups and two ten-groups represent the same collection.
Choose next: An unchanged numeral copied from the model is not enough. Seek a one-to-one/verified-unit explanation on a new regrouping.
Retain the first response, actual range and support; a later corrected or adult-supplied model is a separate record.