Ueno Science Museum holiday guidelines

Hi, again! Am planning to go to the National Museum of Nature and Science in Ueno on April 12, a Tuesday. Based on its website, the info states that they are closed every Monday. But if that Monday is a holiday, they will be opened but then closed on the day after which is Tuesday.
On its website, there is additional info stated:
Ueno District is closed on:
In March It is 7, 14, and 22.
In April It is 11, 18, and 25.

What does this actually mean? I am assuming that this branch of the museum (since there are other branches) in Ueno will be closed on all those dates which are Mondays, right? So if I go on April 12, it will surely be open.

Or does it mean that the whole Ueno has holidays on those days? And so if I go on April 12, the museum will be closed? (Since Monday is a holiday so they will open on that Monday)
I am being very careful as not to waste time since I lumped this museum in our iti together with Imperial, Pokemon Center and Akihabara...Any help is appreciated. Thanks! By the way, I cannot find any contact email in its website thus can't ask them directly.

In general, the museum is closed on Mondays unless Monday is a national holiday in which case it will be closed on the following Tuesday. However, during special exhibitions, there can be some changes to this general rule sometimes, in particular: there can be less closing days than usual.

What does this actually mean?

In March and April, there will be a reduction of closing days, and the museum will be closed only on these days mentioned on the official website.

So if I go on April 12, it will surely be open.

There is no reason why it would be closed on April 12, since April 11 is not a national holiday.

A Planned Exhibition, which does not require an extra fee, is scheduled by National Museum of Nature and Science, Tokyo (nicknamed "Kahaku") from 19 March to 29 May 2011.
This exhibition focuses on coral, and its subhead is "Jewelry from the deep sea" in English.

If you visit Kahaku during weekdays of 11 - 15 April, just after a new semester will practically begin in most schools, I suppose you will not be involved in a jam of visitors. Even so, I still recommend expecting at least 3.5 hours.

A museum in Ueno area can be crowded depending on seasons and exhibitions. I made use of late open hours on Fridays in cases where I guessed the exhibition could be very popular. (When I visited Tokyo National Museum to see a special exhibition on its last day, I had to wait for about 1.5 hour to gain admission!)

What does this actually mean?

These are closed days.
A list of legal holidays in Japan is available on the website of Japan Rail Pass, though some of their names sound not good. (e.g. A holiday on May 4 is actually Greenery Day.)
http://www.japanrailpass.net/eng/en012.html

Thank you, Uji, that cleared things up...

Omotenashi, what do you mean by this?
"Even so, I still recommend expecting at least 3.5 hours. "
1) Is that 3.5 hours the wait time for admittance or the average time spent inside to appreciate it?
2) If there will be school trips during the weekdays, do you recommend me changing my iti to go there on Sunday instead? Or will there be a bigger crowd since it's a weekend?
3) What if I am not into Special Exhibition just the permanent ones, it's still the same line to get into the museum? Because I noticed that entrance fees are different for Special Exhibition and Permanent Exhibition

Thank you very much again!

Is that 3.5 hours the wait time for admittance or the average time spent inside to appreciate it?

Oh..., "to spend in Ueno Park" is missing. This might be enough for you to enjoy both a permanent and a limited time exhibitions. Maybe you take breath in a rest space and/or have a lunch outside. Of course you can skip one exhibition and watch cherry blossoms instead if any.
It depends on persons but I spend about 1 to 2 hours to see one exhibition.

I noticed that entrance fees are different for Special Exhibition and Permanent Exhibition

Kahaku hosts limited time exhibitions of two types: Special Exhibition which requires additional fee and Planned Exhibition which doesn't.

What if I am not into Special Exhibition just the permanent ones, it's still the same line to get into the museum?

Well, it seems that Kahaku usually holds a limited time exhibition in another building. Please follow the instruction there. If my memory is correct, tickets are available at same counters. regardless of exhibitions you hope to see.

If there will be school trips during the weekdays, do you recommend me changing my iti to go there on Sunday instead? Or will there be a bigger crowd since it's a weekend?

I guess a weekday will be better in this season. Most pupils and students of Japanese schools will be at the beginning of a new school year. (Ueno Zoo can be crowded with kids who are eager to see newly-welcomed giant pandas, but good schoolchildren can not do so on a weekday while they have classes.) And probably spring school trips are scheduled mainly in May or later.

Thank you, Omotenashi---will follow your advice to get the most of Ueno:)