SIMCC Games · Teacher guide
Cross Sums
A number crossword: every run of cells adds up to its clue, with no digit twice.
- Trains
- Addition and number bonds · Logical deduction · No digit twice in a run
- Ages
- 8 and up
- In class
- On your own. One device each. Choose First steps: five short lessons, one idea each.
A ten-minute starter
- Show about 2 minDraw two white cells side by side with the clue 3. Ask which digits fill them: only 1 + 2. Then the clue 17: only 8 + 9. Digits are 1 to 9, and no digit appears twice in a run.
- Play about 6 minStudents choose First steps and work through the lessons. Fast finishers try Lower Division: 5 × 5 grids.
- Talk about 2 minAsk a student to show where an across run and a down run cross, and how that fixed one digit.
Questions to ask the class
- Which two-cell clues can be made only one way?Listen for: 3 (1 + 2), 4 (1 + 3), 16 (7 + 9) and 17 (8 + 9).
- A run of three cells adds up to 24. Which digits does it use?Listen for: 7, 8 and 9: the only three different digits that make 24.
- Why can a two-cell run never add up to 2?Listen for: It would need 1 + 1, and a digit cannot repeat in a run.
A common mistake
Using a digit twice in one run, such as 4 + 4 for 8.
How to help: Choose the run: the board lists the ways to make its clue in that many cells. Check (Enter) points out a repeated digit.
Assign it
On the coach dashboard, choose your class under Cohorts. In Assign practice, pick Cross Sums and the drill First steps or Solve the grid, add a due date if you want one, then press Assign. Students find it on their Train page.
Set First steps for a new class, then Solve the grid.
Results show on the dashboard by student and by game once the server has checked them.