The focus of the Two-Digit Number Recognition intervention is to build and identify two-digit numbers. It has two phases. Phase 1: Use base ten blocks and a place value chart to identify two-digit numbers up to 99. Phase 2: Find two-digit numbers in a hundreds chart.

The focus of the Understanding Ten Ones and Some More Ones intervention has two phases. Phase 1: Group ten ones using physical manipulatives to represent a two-digit number and write it. Phase 2: Group ten ones together after drawing pictures to represent a two-digit number and write it.

This problem provides a context in which pupils apply their knowledge of number properties and practice explaining their reasoning. Students decide which of the eight clues provided are necessary in order to determine a specific number on a 0-99 grid. The activity includes teacher notes, hints, sample solutions, a printable pdf of the problem, and a link to a more accessible related problem.

This is a really nice task as it is open to everyone, can be solved in different ways and can also extend to work in combinatorics Ð a nice way of organizing counting. Ask students to work on this task in groups, and to display their results on posters. Often we name studentsÕ different approaches and strategies.

This task helps students build number sense as they practice calculating. The task has more than one solution which is nice. At the end it asks students to write a clue that gives the task only one solution.