We purchased an edu science telescope. model - 70 mm astro-gazer telescope. When we look through the "finderscope" everything is upside down. What do we do to fix this problem?

Channel loc will do the job. One twist will do wonders. about 1/2 turn.

The general rule is 50 times aperture. Your scope is about 2.5 inches-- so 50 times 2.5 or about 125 power--- MAXIMUM and only when the sky is very stable and transparent.

Put the eyepiece with the largest number written on it into the focuser, do not use the 2xbarlow if you have one.

On a reflector the end with the focuser is the UP end the mirror is on the bottom. During the daytime point the scope at a distant object with the above eyepiece in place and practice focusing. Also line up the finderscope with the main telescope tube.

Astronomical telescopes usually show an upside down image. There is a good reason for this- erecting the image needs more bits of glass in the light path, which reduces the amount of light and increases aberrations. Even if this is only slight, astronomers prefer to avoid it, and they don't really care which way up the Moon or Jupiter appear.

The main scope is probably also designed this way, but many amateur scopes now come with an erecting prism or eyepiece attachment that turns the image upright. You may have fitted this and not realise that it is an add-on, and that it is un-natural for an astronomical scope to display upright images.

Yes, but the ones for sale are all metal and not plastic like the ones that came with that scope (sold by Toys R Us).

They may cost more than what the entire telescope cost you.

Eyepieces come in 3 sizes --- .965 inch, 1.25 inch, and 2 inch. Measure the hole in the focuser. The .965 size is a little hard to find since most commercial telescopes use the 1.25 inch size.

Look around here:
http://www.surplusshed.com/

http://shop.telescope-warehouse.com/

http://www.agenaastro.com/

DO NOT buy an Edu Science telescope. We receive many complains on these scopes.

Try this web site for a nice small Dobsonian style telescope, like this one.

http://www.telescope.com/control/telescopes/dobsonian-telescopes/orion-starblast-4*5-astro-reflector-telescope

All astronomical telescopes show the image upside down. It's tradition and there is a good technical reason for this, but you can get an "erecting prism" to make the image upright. This does not have to come from Edu-Science if your eyepieces are the standard size (1.25 inch outside diameter). If you search Amazon or eBay for "erecting prism" you will find a few available. You probably won't want to pay the prices though.

That little scope will NEVER be able to use the 4mm with the 3xbarlow, just too mmuch magnification. The maximum possible magnification for ANY telescope is about 50 times aperture.

Your scope is about 3 inches so 150 power is the maximum.

Read my tips on my profile page.

No sorry. This is just about the worst telescope you can buy. We get more complaints on that brand than just about any other. You might find something at a well stocks hardware store that you can use to fix it???

But why even try to fix it. Buy your son this telescope instead.
http://www.telescope.com/control/product/~category_id=classicdobs/~pcategory=dobsonians/~product_id=09804

and read this web site and my TIPS on my profile page.
http://www.texasastro.org/telescope.php

You cannot buy parts for that small telescope. You can buy a finderscope but it will probably be more than you paid for the entire telescope. Look here:
http://www.telescope.com/control/category/~category_id=finder_scopes