Decimal Addition and Subtraction

Where do I need to add decimal points to make the calculations correct?

The questions can be amended in this spreadsheet, by changing the numbers in the Answers column.

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A decimal investigation

Inspired by playing the excellent Sumaze! 2 game from MEI, here is an investigation that aims to provide some purposeful practice on decimals. The aim is to provide an accessible entry point for all learners with opportunities for depth through generalisation. This slide presentation steps through it although exactly how you move from one part to the next will, of course, depend on the class.

I have included solutions in this spreadsheet although I would be hesitant to display them in this form, as I would prefer that the results are found and discussed as we go along rather than just revealing them at the end.

Area of a triangle

I made these questions to hopefully reinforce the idea of area as the space inside a shape, rather than just the answer you get when you multiply numbers together.  Also I want them to see why the area of the triangle is half the area of the rectangle which it is enclosed within.  I made them using this Geogebra file but then pasted a few to make this worksheet, some with grids then some with just lengths.

A colleague of mine @DrPMaths made this impressive collection of triangles with 3 integer side lengths and an integer height.  Again, they are a great way to check that students are identifying the perpendicular height and multiplying that by the base rather than just multiplying the numbers they are presented with.  There are literally hundreds of them, this is a snapshot from somewhere near the beginning!