Algebra - Families of Facts

During our Algebra unit in maths we looked at the relationships between numbers.
We used equals, greater than and less than signs to create equations.
We took an addition equation and discovered that it didn't matter which way round we added the numbers we still got the same answer. Then, using the same 3 numbers, we created two subtraction equations.
Two addition equations and two subtraction equations - a whole family of facts!