Arrange the ornaments in the box so that no more than
three are in any line horizontally, vertically or diagonally.

Teacher: There are also self-checking versions of this activity for different sized grids:
2 by 2 3 by 3 4 by 4 5 by 5

## A Christmas Mathematics Lesson Starter Of The Day

Topics: Starter | Puzzles | Xmas

You can find many more ChristMaths activities at:

Transum.org/ChristMaths/

• Rachael, Kirsty and Ewan, Leswalt Primary
•
• We really enjoyed doing this.
• Katie Lumsdaine F2 High School Of Dundee, High School Of Dundee
•
• It was challenging but fun and we could use this method to decorate our Christmas tree! :).
• Transum,
•
• After solving the problem for the 4 by 4 grid (not forgetting to check the diagonals) investigate how many different solutions there are. Extend to a 5 by 5 grid and then consider how many ornaments could be arranged on an n by n grid if each column, row and diagonal must contain one empty space.
• Mr Shepherd, St Lawrence Academy, Scunthorpe
•
• 7set4 and 9set4 really enjoyed this, given a minute each and a default fail as soon as a line was completed. We managed to get 14 pupils involved in a 10 minute slot. Exetending to how many possible solutions was beyond them though.

How did you use this starter? Can you suggest how teachers could present or develop this resource? Do you have any comments? It is always useful to receive feedback and helps make this free resource even more useful for Maths teachers anywhere in the world.

Previous Day | This starter is for 11 December | Next Day

There is a printable worksheet to go with this activity.

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Educational Technology on Amazon

 Teacher, do your students have access to computers such as tablets, iPads or Laptops?  This page was really designed for projection on a whiteboard but if you really want the students to have access to it here is a concise URL for a version of this page without the comments: Transum.org/go/?Start=December11 However it would be better to assign one of the student interactive activities below.

Here is the URL which will take them to the student version of this activity.

Transum.org/go/?to=xmas

OR

Investigate other sized ornament boxes using a spreadsheet.

Use "1" to represent an ornament in the box.

Set up row and column totals to check whether your solution is correct

For Students:

For All: