Learn to read the Lancaster University OS map before using it.
Handouts from the outdoor map reading activity http://osmgr.in/a/30272. Map key, attached. Compass with cm/mm scale or a transparent rulers with them.
This session gives the cubs some familiarity with OS maps before using them. The aim is to have everyone able to use the 8 points of the compass, find grid references, identify features on the map and talk about what clothing and equipment they'd need to go outdoors on a long walk. Where older cubs already know the material, they can teach the younger ones.
First make sure everyone knows the four points of the compass, North, East, West and South. The rhyme "Never Eat Shredded Wheat" might help. Then go on to NW, NE, SW and SE. Decide which way in the hut is north and perhaps put a sign up to remind people, then go round the group either asking people to point in the direction you say, or to name the direction you're pointing in. Go round two or three times so everyone gets a couple of goes. If someone's having difficulty, ask them more often so they get more practise thinking about it.
Then show what the key looks like, that the symbols mean different things and that the key tells you what they are, so the map isn't full of little labels that make it harder to see where things are. Pick some features on the map and ask people to identify them. If need be, get a full size OS map out at this point so there's a bigger area to look at, but if you can make sure it's a 1:25000 Explorer map since different maps have different keys.
After that, use the grid references sheet to figure out how to read grid references. Pick some features on the map and get people to work out what the grid reference is, again asking different people so everyone gets a go. Watch how they do it, and if it's wrong ask more people to do it and see what the different answers are- some might be lazy and copy the first answer, some might get it wrong a different way and some should get it right. Talk about the different answers and how people went wrong, and if people have copied, point out that this is how groups get lost- by assuming one person's right and being lazy and not properly doing a second check to make sure.
Then look at the grid references that they'll be trying to find next week on the outdoor activity and have a go at locating them, and perhaps deciding on a good order in which to attempt them from a given starting location.
Finally, talk about what equipment is needed if you're going on a walk in the hills. Obviously a map and compass, but also waterproofs, rugged shoes such as hiking boots because otherwise you'll end up injuring your feet on rocks or getting bad blisters, and clothing that'll keep you warm when you're resting but also can be taken off easily if you get warm while you're walking. Probably also a drink, maybe food, maybe a first aid kit, whistle and torch. If you're going a long way or the weather might be wintry, possibly also a survival/bivvy bag