A lot of people have mentioned that they want to do more work on understanding countours - this is definitely at the very core of what good mountain navigation needs, and of course is one of the most difficult things to 'see' when following the #StayAtHome guidance.
So the first part of your puzzle this week is to pick an area that you know really well, and can 'see' in your mind and then go and have a play with the website at https://contours.axismaps.com/
Here you will be able to build up layers by playing with the settings behind the brush on the top left.
From this you could look at an area (I've chosen the northern Rhinogydd) with lots of different contour detail.
Here are some examples of exactly the same area with different layers of detail.
500m contour intervals
250m contour intervals
100m contour intervals
50m contour intervals
25m contour intervals
10m contour intervals
5m contour intervals
You can have a look here at the equivalent 1:25k OS Map - zoomed in on the centre of the area
If you have a feel for spotting contours see if you can identify the grid reference for this mountain (with the red + on it) in Meirionnydd. Personally, I find the shapes of the river drainages easier to see, before then looking at the peaks.
10m contour intervals.