One of the little known facts is that when you import an image into a web page or document and use the dragging method to reduce it's size - this does not change the size of the uploaded file! So if you put a picture in a document and reduce it to a quarter of the original appearance - the embedded file is still large. It is always good policy to reduce image sizes to the file you want before including them in a document or web page (a blackboard item is in fact a webpage).

You can do this by using photo editing software such as
   
    Microsoft Power Toys image resizer tool (FREE)
        Microsoft Picture Manager (part of the office suite)
        Paint.net (Open Source, Free, available on the network under Library);
        Gimp (Open Source, Free, available on the network under Common Apps)
        IrfanView (Free)
        Almost any photo editing software

One of the advantages of using proper photo editing tools, including Paint.net which is free, is that these will usually resample an image rather than just reduce it. This can help to preserve the sharpness of the reduced image. However these are a little more complicated to use and for most purposes the two simple tools which start the list are quite adequate.